Class: String

Inherits:

Object
String

Includes:: Comparable

Defined in:: string.c

Overview

A String object holds and manipulates an arbitrary sequence of bytes, typically representing characters. String objects may be created using String::new or as literals.

Because of aliasing issues, users of strings should be aware of the methods that modify the contents of a String object. Typically, methods with names ending in “!” modify their receiver, while those without a “!” return a new String. However, there are exceptions, such as String#[]=.

Class Method Summary collapse

.try_convert(obj) ⇒ String^?

Try to convert obj into a String, using to_str method.

Instance Method Summary collapse

#%(arg) ⇒ String

Format—Uses str as a format specification, and returns the result of applying it to arg.
#*(integer) ⇒ String

Copy — Returns a new String containing integer copies of the receiver.
#+(other_str) ⇒ String

Concatenation—Returns a new String containing other_str concatenated to str.
#<< ⇒ Object

Append—Concatenates the given object to str.
#<=>(other_string) ⇒ -1, ...

Comparison—Returns -1, 0, +1 or nil depending on whether string is less than, equal to, or greater than other_string.
#== ⇒ Object

Equality.
#=== ⇒ Object

Equality.
#=~(obj) ⇒ Fixnum^?

Match—If obj is a Regexp, use it as a pattern to match against str,and returns the position the match starts, or nil if there is no match.
#[] ⇒ Object

Element Reference — If passed a single index, returns a substring of one character at that index.
#[]= ⇒ Object

Element Assignment—Replaces some or all of the content of str.
#ascii_only? ⇒ Boolean

Returns true for a string which has only ASCII characters.
#b ⇒ String

Returns a copied string whose encoding is ASCII-8BIT.
#bytes ⇒ Array

Returns an array of bytes in str.
#bytesize ⇒ Integer

Returns the length of str in bytes.
#byteslice ⇒ Object

Byte Reference—If passed a single Fixnum, returns a substring of one byte at that position.
#capitalize ⇒ String

Returns a copy of str with the first character converted to uppercase and the remainder to lowercase.
#capitalize! ⇒ String^?

Modifies str by converting the first character to uppercase and the remainder to lowercase.
#casecmp(other_str) ⇒ -1, ...

Case-insensitive version of String#<=>.
#center(width, padstr = ' ') ⇒ String

Centers str in width.
#chars ⇒ Array

Returns an array of characters in str.
#chomp(separator = $/) ⇒ String

Returns a new String with the given record separator removed from the end of str (if present).
#chomp!(separator = $/) ⇒ String^?

Modifies str in place as described for String#chomp, returning str, or nil if no modifications were made.
#chop ⇒ String

Returns a new String with the last character removed.
#chop! ⇒ String^?

Processes str as for String#chop, returning str, or nil if str is the empty string.
#chr ⇒ String

Returns a one-character string at the beginning of the string.
#clear ⇒ String

Makes string empty.
#codepoints ⇒ Array

Returns an array of the Integer ordinals of the characters in str.
#concat ⇒ Object

Append—Concatenates the given object to str.
#count([other_str]) ⇒ Fixnum

Each other_str parameter defines a set of characters to count.
#crypt(salt_str) ⇒ String

Applies a one-way cryptographic hash to str by invoking the standard library function crypt(3) with the given salt string.
#delete([other_str]) ⇒ String

Returns a copy of str with all characters in the intersection of its arguments deleted.
#delete!([other_str]) ⇒ String^?

Performs a delete operation in place, returning str, or nil if str was not modified.
#downcase ⇒ String

Returns a copy of str with all uppercase letters replaced with their lowercase counterparts.
#downcase! ⇒ String^?

Downcases the contents of str, returning nil if no changes were made.
#dump ⇒ String

Produces a version of str with all non-printing characters replaced by \nnn notation and all special characters escaped.
#each_byte ⇒ Object

Passes each byte in str to the given block, or returns an enumerator if no block is given.
#each_char ⇒ Object

Passes each character in str to the given block, or returns an enumerator if no block is given.
#each_codepoint ⇒ Object

Passes the Integer ordinal of each character in str, also known as a codepoint when applied to Unicode strings to the given block.
#each_line ⇒ Object

Splits str using the supplied parameter as the record separator ($/ by default), passing each substring in turn to the supplied block.
#empty? ⇒ Boolean

Returns true if str has a length of zero.
#encode ⇒ Object

The first form returns a copy of str transcoded to encoding encoding.
#encode! ⇒ Object

The first form transcodes the contents of str from str.encoding to encoding.
#encoding ⇒ Encoding

Returns the Encoding object that represents the encoding of obj.
#end_with?([suffixes]) ⇒ Boolean

Returns true if str ends with one of the suffixes given.
#eql?(other) ⇒ Boolean

Two strings are equal if they have the same length and content.
#force_encoding(encoding) ⇒ String

Changes the encoding to encoding and returns self.
#freeze ⇒ Object
#getbyte(index) ⇒ 0 .. 255

returns the indexth byte as an integer.
#gsub ⇒ Object

Returns a copy of str with the all occurrences of pattern substituted for the second argument.
#gsub! ⇒ Object

Performs the substitutions of String#gsub in place, returning str, or nil if no substitutions were performed.
#hash ⇒ Fixnum

Return a hash based on the string’s length and content.
#hex ⇒ Integer

Treats leading characters from str as a string of hexadecimal digits (with an optional sign and an optional 0x) and returns the corresponding number.
#include?(other_str) ⇒ Boolean

Returns true if str contains the given string or character.
#index ⇒ Object

Returns the index of the first occurrence of the given substring or pattern (regexp) in str.
#new(str = "") ⇒ String constructor

Returns a new string object containing a copy of str.
#replace(other_str) ⇒ String

Replaces the contents and taintedness of str with the corresponding values in other_str.
#insert(index, other_str) ⇒ String

Inserts other_str before the character at the given index, modifying str.
#inspect ⇒ String

Returns a printable version of str, surrounded by quote marks, with special characters escaped.
#intern ⇒ Object

Returns the Symbol corresponding to str, creating the symbol if it did not previously exist.
#length ⇒ Object

Returns the character length of str.
#lines(separator = $/) ⇒ Array

Returns an array of lines in str split using the supplied record separator ($/ by default).
#ljust(integer, padstr = ' ') ⇒ String

If integer is greater than the length of str, returns a new String of length integer with str left justified and padded with padstr; otherwise, returns str.
#lstrip ⇒ String

Returns a copy of str with leading whitespace removed.
#lstrip! ⇒ self^?

Removes leading whitespace from str, returning nil if no change was made.
#match ⇒ Object

Converts pattern to a Regexp (if it isn’t already one), then invokes its match method on str.
#next ⇒ Object

Returns the successor to str.
#next! ⇒ Object

Equivalent to String#succ, but modifies the receiver in place.
#oct ⇒ Integer

Treats leading characters of str as a string of octal digits (with an optional sign) and returns the corresponding number.
#ord ⇒ Integer

Return the Integer ordinal of a one-character string.
#partition ⇒ Object

Searches sep or pattern (regexp) in the string and returns the part before it, the match, and the part after it.
#prepend(other_str) ⇒ String

Prepend—Prepend the given string to str.
#replace(other_str) ⇒ String

Replaces the contents and taintedness of str with the corresponding values in other_str.
#reverse ⇒ String

Returns a new string with the characters from str in reverse order.
#reverse! ⇒ String

Reverses str in place.
#rindex ⇒ Object

Returns the index of the last occurrence of the given substring or pattern (regexp) in str.
#rjust(integer, padstr = ' ') ⇒ String

If integer is greater than the length of str, returns a new String of length integer with str right justified and padded with padstr; otherwise, returns str.
#rpartition ⇒ Object

Searches sep or pattern (regexp) in the string from the end of the string, and returns the part before it, the match, and the part after it.
#rstrip ⇒ String

Returns a copy of str with trailing whitespace removed.
#rstrip! ⇒ self^?

Removes trailing whitespace from str, returning nil if no change was made.
#scan ⇒ Object

Both forms iterate through str, matching the pattern (which may be a Regexp or a String).
#scrub ⇒ Object

If the string is invalid byte sequence then replace invalid bytes with given replacement character, else returns self.
#scrub! ⇒ Object

If the string is invalid byte sequence then replace invalid bytes with given replacement character, else returns self.
#setbyte(index, integer) ⇒ Integer

modifies the indexth byte as integer.
#size ⇒ Object

Returns the character length of str.
#slice ⇒ Object

Element Reference — If passed a single index, returns a substring of one character at that index.
#slice! ⇒ Object

Deletes the specified portion from str, and returns the portion deleted.
#split(pattern = $;, [limit]) ⇒ Array

Divides str into substrings based on a delimiter, returning an array of these substrings.
#squeeze([other_str]) ⇒ String

Builds a set of characters from the other_str parameter(s) using the procedure described for String#count.
#squeeze!([other_str]) ⇒ String^?

Squeezes str in place, returning either str, or nil if no changes were made.
#start_with?([prefixes]) ⇒ Boolean

Returns true if str starts with one of the prefixes given.
#strip ⇒ String

Returns a copy of str with leading and trailing whitespace removed.
#strip! ⇒ String^?

Removes leading and trailing whitespace from str.
#sub ⇒ Object

Returns a copy of str with the first occurrence of pattern replaced by the second argument.
#sub! ⇒ Object

Performs the same substitution as String#sub in-place.
#succ ⇒ Object

Returns the successor to str.
#succ! ⇒ Object

Equivalent to String#succ, but modifies the receiver in place.
#sum(n = 16) ⇒ Integer

Returns a basic n-bit checksum of the characters in str, where n is the optional Fixnum parameter, defaulting to 16.
#swapcase ⇒ String

Returns a copy of str with uppercase alphabetic characters converted to lowercase and lowercase characters converted to uppercase.
#swapcase! ⇒ String^?

Equivalent to String#swapcase, but modifies the receiver in place, returning str, or nil if no changes were made.
#to_c ⇒ Object

Returns a complex which denotes the string form.
#to_f ⇒ Float

Returns the result of interpreting leading characters in str as a floating point number.
#to_i(base = 10) ⇒ Integer

Returns the result of interpreting leading characters in str as an integer base base (between 2 and 36).
#to_r ⇒ Object

Returns a rational which denotes the string form.
#to_s ⇒ Object

Returns the receiver.
#to_str ⇒ Object

Returns the receiver.
#to_sym ⇒ Object

Returns the Symbol corresponding to str, creating the symbol if it did not previously exist.
#tr(from_str, to_str) ⇒ String

Returns a copy of str with the characters in from_str replaced by the corresponding characters in to_str.
#tr!(from_str, to_str) ⇒ String^?

Translates str in place, using the same rules as String#tr.
#tr_s(from_str, to_str) ⇒ String

Processes a copy of str as described under String#tr, then removes duplicate characters in regions that were affected by the translation.
#tr_s!(from_str, to_str) ⇒ String^?

Performs String#tr_s processing on str in place, returning str, or nil if no changes were made.
#unpack(format) ⇒ Array

Decodes str (which may contain binary data) according to the format string, returning an array of each value extracted.
#upcase ⇒ String

Returns a copy of str with all lowercase letters replaced with their uppercase counterparts.
#upcase! ⇒ String^?

Upcases the contents of str, returning nil if no changes were made.
#upto ⇒ Object

Iterates through successive values, starting at str and ending at other_str inclusive, passing each value in turn to the block.
#valid_encoding? ⇒ Boolean

Returns true for a string which encoded correctly.

Methods included from Comparable

#<, #<=, #>, #>=, #between?

Constructor Details

#new(str = "") ⇒ `String`

Returns a new string object containing a copy of str.

# File 'string.c', line 1084

static VALUE
rb_str_init(int argc, VALUE *argv, VALUE str)
{
    VALUE orig;

    if (argc > 0 && rb_scan_args(argc, argv, "01", &orig) == 1)
	rb_str_replace(str, orig);
    return str;
}

Class Method Details

.try_convert(obj) ⇒ `String`^?

Try to convert obj into a String, using to_str method. Returns converted string or nil if obj cannot be converted for any reason.

String.try_convert("str")     #=> "str"
String.try_convert(/re/)      #=> nil

Returns:

(String, nil)

# File 'string.c', line 1696

static VALUE
rb_str_s_try_convert(VALUE dummy, VALUE str)
{
    return rb_check_string_type(str);
}

Instance Method Details

#%(arg) ⇒ `String`

Format—Uses str as a format specification, and returns the result of applying it to arg. If the format specification contains more than one substitution, then arg must be an Array or Hash containing the values to be substituted. See Kernel::sprintf for details of the format string.

"%05d" % 123                              #=> "00123"
"%-5s: %08x" % [ "ID", self.object_id ]   #=> "ID   : 200e14d6"
"foo = %{foo}" % { :foo => 'bar' }        #=> "foo = bar"

Returns:

(String)

# File 'string.c', line 1431

static VALUE
rb_str_format_m(VALUE str, VALUE arg)
{
    volatile VALUE tmp = rb_check_array_type(arg);

    if (!NIL_P(tmp)) {
	return rb_str_format(RARRAY_LENINT(tmp), RARRAY_CONST_PTR(tmp), str);
    }
    return rb_str_format(1, &arg, str);
}

#*(integer) ⇒ `String`

Copy — Returns a new String containing integer copies of the receiver. integer must be greater than or equal to 0.

"Ho! " * 3   #=> "Ho! Ho! Ho! "
"Ho! " * 0   #=> ""

Returns:

(String)

# File 'string.c', line 1383

VALUE
rb_str_times(VALUE str, VALUE times)
{
    VALUE str2;
    long n, len;
    char *ptr2;

    len = NUM2LONG(times);
    if (len < 0) {
	rb_raise(rb_eArgError, "negative argument");
    }
    if (len && LONG_MAX/len <  RSTRING_LEN(str)) {
	rb_raise(rb_eArgError, "argument too big");
    }

    str2 = rb_str_new5(str, 0, len *= RSTRING_LEN(str));
    ptr2 = RSTRING_PTR(str2);
    if (len) {
        n = RSTRING_LEN(str);
        memcpy(ptr2, RSTRING_PTR(str), n);
        while (n <= len/2) {
            memcpy(ptr2 + n, ptr2, n);
            n *= 2;
        }
        memcpy(ptr2 + n, ptr2, len-n);
    }
    ptr2[RSTRING_LEN(str2)] = '\0';
    OBJ_INFECT(str2, str);
    rb_enc_cr_str_copy_for_substr(str2, str);

    return str2;
}

#+(other_str) ⇒ `String`

Concatenation—Returns a new String containing other_str concatenated to str.

"Hello from " + self.to_s   #=> "Hello from main"

Returns:

(String)

# File 'string.c', line 1351

VALUE
rb_str_plus(VALUE str1, VALUE str2)
{
    VALUE str3;
    rb_encoding *enc;

    StringValue(str2);
    enc = rb_enc_check(str1, str2);
    str3 = rb_str_new(0, RSTRING_LEN(str1)+RSTRING_LEN(str2));
    memcpy(RSTRING_PTR(str3), RSTRING_PTR(str1), RSTRING_LEN(str1));
    memcpy(RSTRING_PTR(str3) + RSTRING_LEN(str1),
	   RSTRING_PTR(str2), RSTRING_LEN(str2));
    RSTRING_PTR(str3)[RSTRING_LEN(str3)] = '\0';

    if (OBJ_TAINTED(str1) || OBJ_TAINTED(str2))
	OBJ_TAINT(str3);
    ENCODING_CODERANGE_SET(str3, rb_enc_to_index(enc),
			   ENC_CODERANGE_AND(ENC_CODERANGE(str1), ENC_CODERANGE(str2)));
    return str3;
}

#<<(integer) ⇒ `String` #concat(integer) ⇒ `String` #<<(obj) ⇒ `String` #concat(obj) ⇒ `String`

Append—Concatenates the given object to str. If the object is a Integer, it is considered as a codepoint, and is converted to a character before concatenation.

a = "hello "
a << "world"   #=> "hello world"
a.concat(33)   #=> "hello world!"

Overloads:

#<<(integer) ⇒ String
Returns:
- (String)
#concat(integer) ⇒ String
Returns:
- (String)
#<<(obj) ⇒ String
Returns:
- (String)
#concat(obj) ⇒ String
Returns:
- (String)

# File 'string.c', line 2339

VALUE
rb_str_concat(VALUE str1, VALUE str2)
{
    unsigned int code;
    rb_encoding *enc = STR_ENC_GET(str1);

    if (FIXNUM_P(str2) || RB_TYPE_P(str2, T_BIGNUM)) {
	if (rb_num_to_uint(str2, &code) == 0) {
	}
	else if (FIXNUM_P(str2)) {
	    rb_raise(rb_eRangeError, "%ld out of char range", FIX2LONG(str2));
	}
	else {
	    rb_raise(rb_eRangeError, "bignum out of char range");
	}
    }
    else {
	return rb_str_append(str1, str2);
    }

    if (enc == rb_usascii_encoding()) {
	/* US-ASCII automatically extended to ASCII-8BIT */
	char buf[1];
	buf[0] = (char)code;
	if (code > 0xFF) {
	    rb_raise(rb_eRangeError, "%u out of char range", code);
	}
	rb_str_cat(str1, buf, 1);
	if (code > 127) {
	    rb_enc_associate(str1, rb_ascii8bit_encoding());
	    ENC_CODERANGE_SET(str1, ENC_CODERANGE_VALID);
	}
    }
    else {
	long pos = RSTRING_LEN(str1);
	int cr = ENC_CODERANGE(str1);
	int len;
	char *buf;

	switch (len = rb_enc_codelen(code, enc)) {
	  case ONIGERR_INVALID_CODE_POINT_VALUE:
	    rb_raise(rb_eRangeError, "invalid codepoint 0x%X in %s", code, rb_enc_name(enc));
	    break;
	  case ONIGERR_TOO_BIG_WIDE_CHAR_VALUE:
	  case 0:
	    rb_raise(rb_eRangeError, "%u out of char range", code);
	    break;
	}
	buf = ALLOCA_N(char, len + 1);
	rb_enc_mbcput(code, buf, enc);
	if (rb_enc_precise_mbclen(buf, buf + len + 1, enc) != len) {
	    rb_raise(rb_eRangeError, "invalid codepoint 0x%X in %s", code, rb_enc_name(enc));
	}
	rb_str_resize(str1, pos+len);
	memcpy(RSTRING_PTR(str1) + pos, buf, len);
	if (cr == ENC_CODERANGE_7BIT && code > 127)
	    cr = ENC_CODERANGE_VALID;
	ENC_CODERANGE_SET(str1, cr);
    }
    return str1;
}

#<=>(other_string) ⇒ `-1`, ...

Comparison—Returns -1, 0, +1 or nil depending on whether string is less than, equal to, or greater than other_string.

nil is returned if the two values are incomparable.

If the strings are of different lengths, and the strings are equal when compared up to the shortest length, then the longer string is considered greater than the shorter one.

<=> is the basis for the methods <, <=, >, >=, and between?, included from module Comparable. The method String#== does not use Comparable#==.

"abcdef" <=> "abcde"     #=> 1
"abcdef" <=> "abcdef"    #=> 0
"abcdef" <=> "abcdefg"   #=> -1
"abcdef" <=> "ABCDEF"    #=> 1

Returns:

(-1, 0, +1, nil)

# File 'string.c', line 2595

static VALUE
rb_str_cmp_m(VALUE str1, VALUE str2)
{
    int result;

    if (!RB_TYPE_P(str2, T_STRING)) {
	VALUE tmp = rb_check_funcall(str2, rb_intern("to_str"), 0, 0);
	if (RB_TYPE_P(tmp, T_STRING)) {
	    result = rb_str_cmp(str1, tmp);
	}
	else {
	    return rb_invcmp(str1, str2);
	}
    }
    else {
	result = rb_str_cmp(str1, str2);
    }
    return INT2FIX(result);
}

#==(obj) ⇒ `Boolean` #===(obj) ⇒ `Boolean`

Equality

Returns whether str == obj, similar to Object#==.

If obj is not an instance of String but responds to to_str, then the two strings are compared using case equality Object#===.

Otherwise, returns similarly to String#eql?, comparing length and content.

Overloads:

#==(obj) ⇒ Boolean
Returns:
- (Boolean)
#===(obj) ⇒ Boolean
Returns:
- (Boolean)

# File 'string.c', line 2542

VALUE
rb_str_equal(VALUE str1, VALUE str2)
{
    if (str1 == str2) return Qtrue;
    if (!RB_TYPE_P(str2, T_STRING)) {
	if (!rb_respond_to(str2, rb_intern("to_str"))) {
	    return Qfalse;
	}
	return rb_equal(str2, str1);
    }
    return str_eql(str1, str2);
}

#==(obj) ⇒ `Boolean` #===(obj) ⇒ `Boolean`

Equality

Returns whether str == obj, similar to Object#==.

If obj is not an instance of String but responds to to_str, then the two strings are compared using case equality Object#===.

Otherwise, returns similarly to String#eql?, comparing length and content.

Overloads:

#==(obj) ⇒ Boolean
Returns:
- (Boolean)
#===(obj) ⇒ Boolean
Returns:
- (Boolean)

# File 'string.c', line 2542

VALUE
rb_str_equal(VALUE str1, VALUE str2)
{
    if (str1 == str2) return Qtrue;
    if (!RB_TYPE_P(str2, T_STRING)) {
	if (!rb_respond_to(str2, rb_intern("to_str"))) {
	    return Qfalse;
	}
	return rb_equal(str2, str1);
    }
    return str_eql(str1, str2);
}

#=~(obj) ⇒ `Fixnum`^?

Match—If obj is a Regexp, use it as a pattern to match against str,and returns the position the match starts, or nil if there is no match. Otherwise, invokes obj.=~, passing str as an argument. The default =~ in Object returns nil.

Note: str =~ regexp is not the same as regexp =~ str. Strings captured from named capture groups are assigned to local variables only in the second case.

"cat o' 9 tails" =~ /\d/   #=> 7
"cat o' 9 tails" =~ 9      #=> nil

Returns:

(Fixnum, nil)

# File 'string.c', line 2989

static VALUE
rb_str_match(VALUE x, VALUE y)
{
    if (SPECIAL_CONST_P(y)) goto generic;
    switch (BUILTIN_TYPE(y)) {
      case T_STRING:
	rb_raise(rb_eTypeError, "type mismatch: String given");

      case T_REGEXP:
	return rb_reg_match(y, x);

      generic:
      default:
	return rb_funcall(y, rb_intern("=~"), 1, x);
    }
}

#[](index) ⇒ `String`^? #[](start, length) ⇒ `String`^? #[](range) ⇒ `String`^? #[](regexp) ⇒ `String`^? #[](regexp, capture) ⇒ `String`^? #[](match_str) ⇒ `String`^? #slice(index) ⇒ `String`^? #slice(start, length) ⇒ `String`^? #slice(range) ⇒ `String`^? #slice(regexp) ⇒ `String`^? #slice(regexp, capture) ⇒ `String`^? #slice(match_str) ⇒ `String`^?

Element Reference — If passed a single index, returns a substring of one character at that index. If passed a start index and a length, returns a substring containing length characters starting at the index. If passed a range, its beginning and end are interpreted as offsets delimiting the substring to be returned.

In these three cases, if an index is negative, it is counted from the end of the string. For the start and range cases the starting index is just before a character and an index matching the string’s size. Additionally, an empty string is returned when the starting index for a character range is at the end of the string.

Returns nil if the initial index falls outside the string or the length is negative.

If a Regexp is supplied, the matching portion of the string is returned. If a capture follows the regular expression, which may be a capture group index or name, follows the regular expression that component of the MatchData is returned instead.

If a match_str is given, that string is returned if it occurs in the string.

Returns nil if the regular expression does not match or the match string cannot be found.

a = "hello there"

a[1]                   #=> "e"
a[2, 3]                #=> "llo"
a[2..3]                #=> "ll"

a[-3, 2]               #=> "er"
a[7..-2]               #=> "her"
a[-4..-2]              #=> "her"
a[-2..-4]              #=> ""

a[11, 0]               #=> ""
a[11]                  #=> nil
a[12, 0]               #=> nil
a[12..-1]              #=> nil

a[/[aeiou](.)\1/]      #=> "ell"
a[/[aeiou](.)\1/, 0]   #=> "ell"
a[/[aeiou](.)\1/, 1]   #=> "l"
a[/[aeiou](.)\1/, 2]   #=> nil

a[/(?<vowel>[aeiou])(?<non_vowel>[^aeiou])/, "non_vowel"] #=> "l"
a[/(?<vowel>[aeiou])(?<non_vowel>[^aeiou])/, "vowel"]     #=> "e"

a["lo"]                #=> "lo"
a["bye"]               #=> nil

Overloads:

#[](index) ⇒ String^?
Returns:
- (String, nil)
#[](start, length) ⇒ String^?
Returns:
- (String, nil)
#[](range) ⇒ String^?
Returns:
- (String, nil)
#[](regexp) ⇒ String^?
Returns:
- (String, nil)
#[](regexp, capture) ⇒ String^?
Returns:
- (String, nil)
#[](match_str) ⇒ String^?
Returns:
- (String, nil)
#slice(index) ⇒ String^?
Returns:
- (String, nil)
#slice(start, length) ⇒ String^?
Returns:
- (String, nil)
#slice(range) ⇒ String^?
Returns:
- (String, nil)
#slice(regexp) ⇒ String^?
Returns:
- (String, nil)
#slice(regexp, capture) ⇒ String^?
Returns:
- (String, nil)
#slice(match_str) ⇒ String^?
Returns:
- (String, nil)

# File 'string.c', line 3621

static VALUE
rb_str_aref_m(int argc, VALUE *argv, VALUE str)
{
    if (argc == 2) {
	if (RB_TYPE_P(argv[0], T_REGEXP)) {
	    return rb_str_subpat(str, argv[0], argv[1]);
	}
	return rb_str_substr(str, NUM2LONG(argv[0]), NUM2LONG(argv[1]));
    }
    rb_check_arity(argc, 1, 2);
    return rb_str_aref(str, argv[0]);
}

#[]=(fixnum) ⇒ `Object` #[]=(fixnum, fixnum) ⇒ `Object` #[]=(range) ⇒ `Object` #[]=(regexp) ⇒ `Object` #[]=(regexp, fixnum) ⇒ `Object` #[]=(regexp, name) ⇒ `Object` #[]=(other_str) ⇒ `Object`

Element Assignment—Replaces some or all of the content of str. The portion of the string affected is determined using the same criteria as String#[]. If the replacement string is not the same length as the text it is replacing, the string will be adjusted accordingly. If the regular expression or string is used as the index doesn’t match a position in the string, IndexError is raised. If the regular expression form is used, the optional second Fixnum allows you to specify which portion of the match to replace (effectively using the MatchData indexing rules. The forms that take a Fixnum will raise an IndexError if the value is out of range; the Range form will raise a RangeError, and the Regexp and String will raise an IndexError on negative match.

# File 'string.c', line 3849

static VALUE
rb_str_aset_m(int argc, VALUE *argv, VALUE str)
{
    if (argc == 3) {
	if (RB_TYPE_P(argv[0], T_REGEXP)) {
	    rb_str_subpat_set(str, argv[0], argv[1], argv[2]);
	}
	else {
	    rb_str_splice(str, NUM2LONG(argv[0]), NUM2LONG(argv[1]), argv[2]);
	}
	return argv[2];
    }
    rb_check_arity(argc, 2, 3);
    return rb_str_aset(str, argv[0], argv[1]);
}

#ascii_only? ⇒ `Boolean`

Returns true for a string which has only ASCII characters.

"abc".force_encoding("UTF-8").ascii_only?          #=> true
"abc\u{6666}".force_encoding("UTF-8").ascii_only?  #=> false

Returns:

(Boolean)

Returns:

(Boolean)

# File 'string.c', line 7949

static VALUE
rb_str_is_ascii_only_p(VALUE str)
{
    int cr = rb_enc_str_coderange(str);

    return cr == ENC_CODERANGE_7BIT ? Qtrue : Qfalse;
}

#b ⇒ `String`

Returns a copied string whose encoding is ASCII-8BIT.

Returns:

(String)

# File 'string.c', line 7910

static VALUE
rb_str_b(VALUE str)
{
    VALUE str2 = str_alloc(rb_cString);
    str_replace_shared_without_enc(str2, str);
    OBJ_INFECT(str2, str);
    ENC_CODERANGE_CLEAR(str2);
    return str2;
}

#bytes ⇒ `Array`

Returns an array of bytes in str. This is a shorthand for str.each_byte.to_a.

If a block is given, which is a deprecated form, works the same as each_byte.

Returns:

(Array)

# File 'string.c', line 6668

static VALUE
rb_str_bytes(VALUE str)
{
    return rb_str_enumerate_bytes(str, 1);
}

#bytesize ⇒ `Integer`

Returns the length of str in bytes.

"\x80\u3042".bytesize  #=> 4
"hello".bytesize       #=> 5

Returns:

(Integer)

# File 'string.c', line 1316

static VALUE
rb_str_bytesize(VALUE str)
{
    return LONG2NUM(RSTRING_LEN(str));
}

#byteslice(fixnum) ⇒ `String`^? #byteslice(fixnum, fixnum) ⇒ `String`^? #byteslice(range) ⇒ `String`^?

Byte Reference—If passed a single Fixnum, returns a substring of one byte at that position. If passed two Fixnum objects, returns a substring starting at the offset given by the first, and a length given by the second. If given a Range, a substring containing bytes at offsets given by the range is returned. In all three cases, if an offset is negative, it is counted from the end of str. Returns nil if the initial offset falls outside the string, the length is negative, or the beginning of the range is greater than the end. The encoding of the resulted string keeps original encoding.

"hello".byteslice(1)     #=> "e"
"hello".byteslice(-1)    #=> "o"
"hello".byteslice(1, 2)  #=> "el"
"\x80\u3042".byteslice(1, 3) #=> "\u3042"
"\x03\u3042\xff".byteslice(1..3) #=> "\u3042"

Overloads:

#byteslice(fixnum) ⇒ String^?
Returns:
- (String, nil)
#byteslice(fixnum, fixnum) ⇒ String^?
Returns:
- (String, nil)
#byteslice(range) ⇒ String^?
Returns:
- (String, nil)

# File 'string.c', line 4519

static VALUE
rb_str_byteslice(int argc, VALUE *argv, VALUE str)
{
    if (argc == 2) {
	return str_byte_substr(str, NUM2LONG(argv[0]), NUM2LONG(argv[1]));
    }
    rb_check_arity(argc, 1, 2);
    return str_byte_aref(str, argv[0]);
}

#capitalize ⇒ `String`

Returns a copy of str with the first character converted to uppercase and the remainder to lowercase. Note: case conversion is effective only in ASCII region.

"hello".capitalize    #=> "Hello"
"HELLO".capitalize    #=> "Hello"
"123ABC".capitalize   #=> "123abc"

Returns:

(String)

# File 'string.c', line 5267

static VALUE
rb_str_capitalize(VALUE str)
{
    str = rb_str_dup(str);
    rb_str_capitalize_bang(str);
    return str;
}

#capitalize! ⇒ `String`^?

Modifies str by converting the first character to uppercase and the remainder to lowercase. Returns nil if no changes are made. Note: case conversion is effective only in ASCII region.

a = "hello"
a.capitalize!   #=> "Hello"
a               #=> "Hello"
a.capitalize!   #=> nil

Returns:

(String, nil)

# File 'string.c', line 5219

static VALUE
rb_str_capitalize_bang(VALUE str)
{
    rb_encoding *enc;
    char *s, *send;
    int modify = 0;
    unsigned int c;
    int n;

    str_modify_keep_cr(str);
    enc = STR_ENC_GET(str);
    rb_str_check_dummy_enc(enc);
    if (RSTRING_LEN(str) == 0 || !RSTRING_PTR(str)) return Qnil;
    s = RSTRING_PTR(str); send = RSTRING_END(str);

    c = rb_enc_codepoint_len(s, send, &n, enc);
    if (rb_enc_islower(c, enc)) {
	rb_enc_mbcput(rb_enc_toupper(c, enc), s, enc);
	modify = 1;
    }
    s += n;
    while (s < send) {
	c = rb_enc_codepoint_len(s, send, &n, enc);
	if (rb_enc_isupper(c, enc)) {
	    rb_enc_mbcput(rb_enc_tolower(c, enc), s, enc);
	    modify = 1;
	}
	s += n;
    }

    if (modify) return str;
    return Qnil;
}

#casecmp(other_str) ⇒ `-1`, ...

Case-insensitive version of String#<=>.

"abcdef".casecmp("abcde")     #=> 1
"aBcDeF".casecmp("abcdef")    #=> 0
"abcdef".casecmp("abcdefg")   #=> -1
"abcdef".casecmp("ABCDEF")    #=> 0

Returns:

(-1, 0, +1, nil)

# File 'string.c', line 2627

static VALUE
rb_str_casecmp(VALUE str1, VALUE str2)
{
    long len;
    rb_encoding *enc;
    char *p1, *p1end, *p2, *p2end;

    StringValue(str2);
    enc = rb_enc_compatible(str1, str2);
    if (!enc) {
	return Qnil;
    }

    p1 = RSTRING_PTR(str1); p1end = RSTRING_END(str1);
    p2 = RSTRING_PTR(str2); p2end = RSTRING_END(str2);
    if (single_byte_optimizable(str1) && single_byte_optimizable(str2)) {
	while (p1 < p1end && p2 < p2end) {
	    if (*p1 != *p2) {
		unsigned int c1 = TOUPPER(*p1 & 0xff);
		unsigned int c2 = TOUPPER(*p2 & 0xff);
                if (c1 != c2)
                    return INT2FIX(c1 < c2 ? -1 : 1);
	    }
	    p1++;
	    p2++;
	}
    }
    else {
	while (p1 < p1end && p2 < p2end) {
            int l1, c1 = rb_enc_ascget(p1, p1end, &l1, enc);
            int l2, c2 = rb_enc_ascget(p2, p2end, &l2, enc);

            if (0 <= c1 && 0 <= c2) {
                c1 = TOUPPER(c1);
                c2 = TOUPPER(c2);
                if (c1 != c2)
                    return INT2FIX(c1 < c2 ? -1 : 1);
            }
            else {
                int r;
                l1 = rb_enc_mbclen(p1, p1end, enc);
                l2 = rb_enc_mbclen(p2, p2end, enc);
                len = l1 < l2 ? l1 : l2;
                r = memcmp(p1, p2, len);
                if (r != 0)
                    return INT2FIX(r < 0 ? -1 : 1);
                if (l1 != l2)
                    return INT2FIX(l1 < l2 ? -1 : 1);
            }
	    p1 += l1;
	    p2 += l2;
	}
    }
    if (RSTRING_LEN(str1) == RSTRING_LEN(str2)) return INT2FIX(0);
    if (RSTRING_LEN(str1) > RSTRING_LEN(str2)) return INT2FIX(1);
    return INT2FIX(-1);
}

#center(width, padstr = ' ') ⇒ `String`

Centers str in width. If width is greater than the length of str, returns a new String of length width with str centered and padded with padstr; otherwise, returns str.

"hello".center(4)         #=> "hello"
"hello".center(20)        #=> "       hello        "
"hello".center(20, '123') #=> "1231231hello12312312"

Returns:

(String)

# File 'string.c', line 7710

static VALUE
rb_str_center(int argc, VALUE *argv, VALUE str)
{
    return rb_str_justify(argc, argv, str, 'c');
}

#chars ⇒ `Array`

Returns an array of characters in str. This is a shorthand for str.each_char.to_a.

If a block is given, which is a deprecated form, works the same as each_char.

Returns:

(Array)

# File 'string.c', line 6774

static VALUE
rb_str_chars(VALUE str)
{
    return rb_str_enumerate_chars(str, 1);
}

#chomp(separator = $/) ⇒ `String`

Returns a new String with the given record separator removed from the end of str (if present). If $/ has not been changed from the default Ruby record separator, then chomp also removes carriage return characters (that is it will remove \n, \r, and \r\n). If $/ is an empty string, it will remove all trailing newlines from the string.

"hello".chomp                #=> "hello"
"hello\n".chomp              #=> "hello"
"hello\r\n".chomp            #=> "hello"
"hello\n\r".chomp            #=> "hello\n"
"hello\r".chomp              #=> "hello"
"hello \n there".chomp       #=> "hello \n there"
"hello".chomp("llo")         #=> "he"
"hello\r\n\r\n".chomp('')    #=> "hello"
"hello\r\n\r\r\n".chomp('')  #=> "hello\r\n\r"

Returns:

(String)

# File 'string.c', line 7075

static VALUE
rb_str_chomp(int argc, VALUE *argv, VALUE str)
{
    str = rb_str_dup(str);
    rb_str_chomp_bang(argc, argv, str);
    return str;
}

#chomp!(separator = $/) ⇒ `String`^?

Modifies str in place as described for String#chomp, returning str, or nil if no modifications were made.

Returns:

(String, nil)

# File 'string.c', line 6952

static VALUE
rb_str_chomp_bang(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    VALUE rs;
    int newline;
    char *p, *pp, *e;
    long len, rslen;

    str_modify_keep_cr(str);
    len = RSTRING_LEN(str);
    if (len == 0) return Qnil;
    p = RSTRING_PTR(str);
    e = p + len;
    if (argc == 0) {
	rs = rb_rs;
	if (rs == rb_default_rs) {
	  smart_chomp:
	    enc = rb_enc_get(str);
	    if (rb_enc_mbminlen(enc) > 1) {
		pp = rb_enc_left_char_head(p, e-rb_enc_mbminlen(enc), e, enc);
		if (rb_enc_is_newline(pp, e, enc)) {
		    e = pp;
		}
		pp = e - rb_enc_mbminlen(enc);
		if (pp >= p) {
		    pp = rb_enc_left_char_head(p, pp, e, enc);
		    if (rb_enc_ascget(pp, e, 0, enc) == '\r') {
			e = pp;
		    }
		}
		if (e == RSTRING_END(str)) {
		    return Qnil;
		}
		len = e - RSTRING_PTR(str);
		STR_SET_LEN(str, len);
	    }
	    else {
		if (RSTRING_PTR(str)[len-1] == '\n') {
		    STR_DEC_LEN(str);
		    if (RSTRING_LEN(str) > 0 &&
			RSTRING_PTR(str)[RSTRING_LEN(str)-1] == '\r') {
			STR_DEC_LEN(str);
		    }
		}
		else if (RSTRING_PTR(str)[len-1] == '\r') {
		    STR_DEC_LEN(str);
		}
		else {
		    return Qnil;
		}
	    }
	    RSTRING_PTR(str)[RSTRING_LEN(str)] = '\0';
	    return str;
	}
    }
    else {
	rb_scan_args(argc, argv, "01", &rs);
    }
    if (NIL_P(rs)) return Qnil;
    StringValue(rs);
    rslen = RSTRING_LEN(rs);
    if (rslen == 0) {
	while (len>0 && p[len-1] == '\n') {
	    len--;
	    if (len>0 && p[len-1] == '\r')
		len--;
	}
	if (len < RSTRING_LEN(str)) {
	    STR_SET_LEN(str, len);
	    RSTRING_PTR(str)[len] = '\0';
	    return str;
	}
	return Qnil;
    }
    if (rslen > len) return Qnil;
    newline = RSTRING_PTR(rs)[rslen-1];
    if (rslen == 1 && newline == '\n')
	goto smart_chomp;

    enc = rb_enc_check(str, rs);
    if (is_broken_string(rs)) {
	return Qnil;
    }
    pp = e - rslen;
    if (p[len-1] == newline &&
	(rslen <= 1 ||
	 memcmp(RSTRING_PTR(rs), pp, rslen) == 0)) {
	if (rb_enc_left_char_head(p, pp, e, enc) != pp)
	    return Qnil;
	if (ENC_CODERANGE(str) != ENC_CODERANGE_7BIT) {
	    ENC_CODERANGE_CLEAR(str);
	}
	STR_SET_LEN(str, RSTRING_LEN(str) - rslen);
	RSTRING_PTR(str)[RSTRING_LEN(str)] = '\0';
	return str;
    }
    return Qnil;
}

#chop ⇒ `String`

Returns a new String with the last character removed. If the string ends with \r\n, both characters are removed. Applying chop to an empty string returns an empty string. String#chomp is often a safer alternative, as it leaves the string unchanged if it doesn’t end in a record separator.

"string\r\n".chop   #=> "string"
"string\n\r".chop   #=> "string\n"
"string\n".chop     #=> "string"
"string".chop       #=> "strin"
"x".chop.chop       #=> ""

Returns:

(String)

# File 'string.c', line 6937

static VALUE
rb_str_chop(VALUE str)
{
    return rb_str_subseq(str, 0, chopped_length(str));
}

#chop! ⇒ `String`^?

Processes str as for String#chop, returning str, or nil if str is the empty string. See also String#chomp!.

Returns:

(String, nil)

# File 'string.c', line 6902

static VALUE
rb_str_chop_bang(VALUE str)
{
    str_modify_keep_cr(str);
    if (RSTRING_LEN(str) > 0) {
	long len;
	len = chopped_length(str);
	STR_SET_LEN(str, len);
	RSTRING_PTR(str)[len] = '\0';
	if (ENC_CODERANGE(str) != ENC_CODERANGE_7BIT) {
	    ENC_CODERANGE_CLEAR(str);
	}
	return str;
    }
    return Qnil;
}

#chr ⇒ `String`

Returns a one-character string at the beginning of the string.

a = "abcde"
a.chr    #=> "a"

Returns:

(String)

# File 'string.c', line 4358

static VALUE
rb_str_chr(VALUE str)
{
    return rb_str_substr(str, 0, 1);
}

#clear ⇒ `String`

Makes string empty.

a = "abcde"
a.clear    #=> ""

Returns:

(String)

# File 'string.c', line 4334

static VALUE
rb_str_clear(VALUE str)
{
    str_discard(str);
    STR_SET_EMBED(str);
    STR_SET_EMBED_LEN(str, 0);
    RSTRING_PTR(str)[0] = 0;
    if (rb_enc_asciicompat(STR_ENC_GET(str)))
	ENC_CODERANGE_SET(str, ENC_CODERANGE_7BIT);
    else
	ENC_CODERANGE_SET(str, ENC_CODERANGE_VALID);
    return str;
}

#codepoints ⇒ `Array`

Returns an array of the Integer ordinals of the characters in str. This is a shorthand for str.each_codepoint.to_a.

If a block is given, which is a deprecated form, works the same as each_codepoint.

Returns:

(Array)

# File 'string.c', line 6868

static VALUE
rb_str_codepoints(VALUE str)
{
    return rb_str_enumerate_codepoints(str, 1);
}

#<<(integer) ⇒ `String` #concat(integer) ⇒ `String` #<<(obj) ⇒ `String` #concat(obj) ⇒ `String`

Append—Concatenates the given object to str. If the object is a Integer, it is considered as a codepoint, and is converted to a character before concatenation.

a = "hello "
a << "world"   #=> "hello world"
a.concat(33)   #=> "hello world!"

Overloads:

#<<(integer) ⇒ String
Returns:
- (String)
#concat(integer) ⇒ String
Returns:
- (String)
#<<(obj) ⇒ String
Returns:
- (String)
#concat(obj) ⇒ String
Returns:
- (String)

# File 'string.c', line 2339

VALUE
rb_str_concat(VALUE str1, VALUE str2)
{
    unsigned int code;
    rb_encoding *enc = STR_ENC_GET(str1);

    if (FIXNUM_P(str2) || RB_TYPE_P(str2, T_BIGNUM)) {
	if (rb_num_to_uint(str2, &code) == 0) {
	}
	else if (FIXNUM_P(str2)) {
	    rb_raise(rb_eRangeError, "%ld out of char range", FIX2LONG(str2));
	}
	else {
	    rb_raise(rb_eRangeError, "bignum out of char range");
	}
    }
    else {
	return rb_str_append(str1, str2);
    }

    if (enc == rb_usascii_encoding()) {
	/* US-ASCII automatically extended to ASCII-8BIT */
	char buf[1];
	buf[0] = (char)code;
	if (code > 0xFF) {
	    rb_raise(rb_eRangeError, "%u out of char range", code);
	}
	rb_str_cat(str1, buf, 1);
	if (code > 127) {
	    rb_enc_associate(str1, rb_ascii8bit_encoding());
	    ENC_CODERANGE_SET(str1, ENC_CODERANGE_VALID);
	}
    }
    else {
	long pos = RSTRING_LEN(str1);
	int cr = ENC_CODERANGE(str1);
	int len;
	char *buf;

	switch (len = rb_enc_codelen(code, enc)) {
	  case ONIGERR_INVALID_CODE_POINT_VALUE:
	    rb_raise(rb_eRangeError, "invalid codepoint 0x%X in %s", code, rb_enc_name(enc));
	    break;
	  case ONIGERR_TOO_BIG_WIDE_CHAR_VALUE:
	  case 0:
	    rb_raise(rb_eRangeError, "%u out of char range", code);
	    break;
	}
	buf = ALLOCA_N(char, len + 1);
	rb_enc_mbcput(code, buf, enc);
	if (rb_enc_precise_mbclen(buf, buf + len + 1, enc) != len) {
	    rb_raise(rb_eRangeError, "invalid codepoint 0x%X in %s", code, rb_enc_name(enc));
	}
	rb_str_resize(str1, pos+len);
	memcpy(RSTRING_PTR(str1) + pos, buf, len);
	if (cr == ENC_CODERANGE_7BIT && code > 127)
	    cr = ENC_CODERANGE_VALID;
	ENC_CODERANGE_SET(str1, cr);
    }
    return str1;
}

#count([other_str]) ⇒ `Fixnum`

Each other_str parameter defines a set of characters to count. The intersection of these sets defines the characters to count in str. Any other_str that starts with a caret ^ is negated. The sequence c1-c2 means all characters between c1 and c2. The backslash character </code> can be used to escape <code>^ or - and is otherwise ignored unless it appears at the end of a sequence or the end of a other_str.

a = "hello world"
a.count "lo"                   #=> 5
a.count "lo", "o"              #=> 2
a.count "hello", "^l"          #=> 4
a.count "ej-m"                 #=> 4

"hello^world".count "\\^aeiou" #=> 4
"hello-world".count "a\\-eo"   #=> 4

c = "hello world\\r\\n"
c.count "\\"                   #=> 2
c.count "\\A"                  #=> 0
c.count "X-\\w"                #=> 3

Returns:

(Fixnum)

# File 'string.c', line 6057

static VALUE
rb_str_count(int argc, VALUE *argv, VALUE str)
{
    char table[TR_TABLE_SIZE];
    rb_encoding *enc = 0;
    VALUE del = 0, nodel = 0, tstr;
    char *s, *send;
    int i;
    int ascompat;

    rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);

    tstr = argv[0];
    StringValue(tstr);
    enc = rb_enc_check(str, tstr);
    if (argc == 1) {
	const char *ptstr;
	if (RSTRING_LEN(tstr) == 1 && rb_enc_asciicompat(enc) &&
	    (ptstr = RSTRING_PTR(tstr),
	     ONIGENC_IS_ALLOWED_REVERSE_MATCH(enc, (const unsigned char *)ptstr, (const unsigned char *)ptstr+1)) &&
	    !is_broken_string(str)) {
	    int n = 0;
	    int clen;
	    unsigned char c = rb_enc_codepoint_len(ptstr, ptstr+1, &clen, enc);

	    s = RSTRING_PTR(str);
	    if (!s || RSTRING_LEN(str) == 0) return INT2FIX(0);
	    send = RSTRING_END(str);
	    while (s < send) {
		if (*(unsigned char*)s++ == c) n++;
	    }
	    return INT2NUM(n);
	}
    }

    tr_setup_table(tstr, table, TRUE, &del, &nodel, enc);
    for (i=1; i<argc; i++) {
	tstr = argv[i];
	StringValue(tstr);
	enc = rb_enc_check(str, tstr);
	tr_setup_table(tstr, table, FALSE, &del, &nodel, enc);
    }

    s = RSTRING_PTR(str);
    if (!s || RSTRING_LEN(str) == 0) return INT2FIX(0);
    send = RSTRING_END(str);
    ascompat = rb_enc_asciicompat(enc);
    i = 0;
    while (s < send) {
	unsigned int c;

	if (ascompat && (c = *(unsigned char*)s) < 0x80) {
	    if (table[c]) {
		i++;
	    }
	    s++;
	}
	else {
	    int clen;
	    c = rb_enc_codepoint_len(s, send, &clen, enc);
	    if (tr_find(c, table, del, nodel)) {
		i++;
	    }
	    s += clen;
	}
    }

    return INT2NUM(i);
}

#crypt(salt_str) ⇒ `String`

Applies a one-way cryptographic hash to str by invoking the standard library function crypt(3) with the given salt string. While the format and the result are system and implementation dependent, using a salt matching the regular expression \A[a-zA-Z0-9./]{2} should be valid and safe on any platform, in which only the first two characters are significant.

This method is for use in system specific scripts, so if you want a cross-platform hash function consider using Digest or OpenSSL instead.

Returns:

(String)

# File 'string.c', line 7412

static VALUE
rb_str_crypt(VALUE str, VALUE salt)
{
    extern char *crypt(const char *, const char *);
    VALUE result;
    const char *s, *saltp;
    char *res;
#ifdef BROKEN_CRYPT
    char salt_8bit_clean[3];
#endif

    StringValue(salt);
    if (RSTRING_LEN(salt) < 2)
	rb_raise(rb_eArgError, "salt too short (need >=2 bytes)");

    s = RSTRING_PTR(str);
    if (!s) s = "";
    saltp = RSTRING_PTR(salt);
#ifdef BROKEN_CRYPT
    if (!ISASCII((unsigned char)saltp[0]) || !ISASCII((unsigned char)saltp[1])) {
	salt_8bit_clean[0] = saltp[0] & 0x7f;
	salt_8bit_clean[1] = saltp[1] & 0x7f;
	salt_8bit_clean[2] = '\0';
	saltp = salt_8bit_clean;
    }
#endif
    res = crypt(s, saltp);
    if (!res) {
	rb_sys_fail("crypt");
    }
    result = rb_str_new2(res);
    OBJ_INFECT(result, str);
    OBJ_INFECT(result, salt);
    return result;
}

#delete([other_str]) ⇒ `String`

Returns a copy of str with all characters in the intersection of its arguments deleted. Uses the same rules for building the set of characters as String#count.

"hello".delete "l","lo"        #=> "heo"
"hello".delete "lo"            #=> "he"
"hello".delete "aeiou", "^e"   #=> "hell"
"hello".delete "ej-m"          #=> "ho"

Returns:

(String)

# File 'string.c', line 5877

static VALUE
rb_str_delete(int argc, VALUE *argv, VALUE str)
{
    str = rb_str_dup(str);
    rb_str_delete_bang(argc, argv, str);
    return str;
}

#delete!([other_str]) ⇒ `String`^?

Performs a delete operation in place, returning str, or nil if str was not modified.

Returns:

(String, nil)

# File 'string.c', line 5801

static VALUE
rb_str_delete_bang(int argc, VALUE *argv, VALUE str)
{
    char squeez[TR_TABLE_SIZE];
    rb_encoding *enc = 0;
    char *s, *send, *t;
    VALUE del = 0, nodel = 0;
    int modify = 0;
    int i, ascompat, cr;

    if (RSTRING_LEN(str) == 0 || !RSTRING_PTR(str)) return Qnil;
    rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);
    for (i=0; i<argc; i++) {
	VALUE s = argv[i];

	StringValue(s);
	enc = rb_enc_check(str, s);
	tr_setup_table(s, squeez, i==0, &del, &nodel, enc);
    }

    str_modify_keep_cr(str);
    ascompat = rb_enc_asciicompat(enc);
    s = t = RSTRING_PTR(str);
    send = RSTRING_END(str);
    cr = ascompat ? ENC_CODERANGE_7BIT : ENC_CODERANGE_VALID;
    while (s < send) {
	unsigned int c;
	int clen;

	if (ascompat && (c = *(unsigned char*)s) < 0x80) {
	    if (squeez[c]) {
		modify = 1;
	    }
	    else {
		if (t != s) *t = c;
		t++;
	    }
	    s++;
	}
	else {
	    c = rb_enc_codepoint_len(s, send, &clen, enc);

	    if (tr_find(c, squeez, del, nodel)) {
		modify = 1;
	    }
	    else {
		if (t != s) rb_enc_mbcput(c, t, enc);
		t += clen;
		if (cr == ENC_CODERANGE_7BIT) cr = ENC_CODERANGE_VALID;
	    }
	    s += clen;
	}
    }
    *t = '\0';
    STR_SET_LEN(str, t - RSTRING_PTR(str));
    ENC_CODERANGE_SET(str, cr);

    if (modify) return str;
    return Qnil;
}

#downcase ⇒ `String`

Returns a copy of str with all uppercase letters replaced with their lowercase counterparts. The operation is locale insensitive—only characters “A” to “Z” are affected. Note: case replacement is effective only in ASCII region.

"hEllO".downcase   #=> "hello"

Returns:

(String)

# File 'string.c', line 5196

static VALUE
rb_str_downcase(VALUE str)
{
    str = rb_str_dup(str);
    rb_str_downcase_bang(str);
    return str;
}

#downcase! ⇒ `String`^?

Downcases the contents of str, returning nil if no changes were made. Note: case replacement is effective only in ASCII region.

Returns:

(String, nil)

# File 'string.c', line 5131

static VALUE
rb_str_downcase_bang(VALUE str)
{
    rb_encoding *enc;
    char *s, *send;
    int modify = 0;

    str_modify_keep_cr(str);
    enc = STR_ENC_GET(str);
    rb_str_check_dummy_enc(enc);
    s = RSTRING_PTR(str); send = RSTRING_END(str);
    if (single_byte_optimizable(str)) {
	while (s < send) {
	    unsigned int c = *(unsigned char*)s;

	    if (rb_enc_isascii(c, enc) && 'A' <= c && c <= 'Z') {
		*s = 'a' + (c - 'A');
		modify = 1;
	    }
	    s++;
	}
    }
    else {
	int ascompat = rb_enc_asciicompat(enc);

	while (s < send) {
	    unsigned int c;
	    int n;

	    if (ascompat && (c = *(unsigned char*)s) < 0x80) {
		if (rb_enc_isascii(c, enc) && 'A' <= c && c <= 'Z') {
		    *s = 'a' + (c - 'A');
		    modify = 1;
		}
		s++;
	    }
	    else {
		c = rb_enc_codepoint_len(s, send, &n, enc);
		if (rb_enc_isupper(c, enc)) {
		    /* assuming toupper returns codepoint with same size */
		    rb_enc_mbcput(rb_enc_tolower(c, enc), s, enc);
		    modify = 1;
		}
		s += n;
	    }
	}
    }

    if (modify) return str;
    return Qnil;
}

#dump ⇒ `String`

Produces a version of str with all non-printing characters replaced by \nnn notation and all special characters escaped.

"hello \n ''".dump  #=> "\"hello \\n ''\"

Returns:

(String)

# File 'string.c', line 4898

VALUE
rb_str_dump(VALUE str)
{
    rb_encoding *enc = rb_enc_get(str);
    long len;
    const char *p, *pend;
    char *q, *qend;
    VALUE result;
    int u8 = (enc == rb_utf8_encoding());

    len = 2;			/* "" */
    p = RSTRING_PTR(str); pend = p + RSTRING_LEN(str);
    while (p < pend) {
	unsigned char c = *p++;
	switch (c) {
	  case '"':  case '\\':
	  case '\n': case '\r':
	  case '\t': case '\f':
	  case '\013': case '\010': case '\007': case '\033':
	    len += 2;
	    break;

	  case '#':
	    len += IS_EVSTR(p, pend) ? 2 : 1;
	    break;

	  default:
	    if (ISPRINT(c)) {
		len++;
	    }
	    else {
		if (u8 && c > 0x7F) {	/* \u{NN} */
		    int n = rb_enc_precise_mbclen(p-1, pend, enc);
		    if (MBCLEN_CHARFOUND_P(n)) {
			unsigned int cc = rb_enc_mbc_to_codepoint(p-1, pend, enc);
			while (cc >>= 4) len++;
			len += 5;
			p += MBCLEN_CHARFOUND_LEN(n)-1;
			break;
		    }
		}
		len += 4;	/* \xNN */
	    }
	    break;
	}
    }
    if (!rb_enc_asciicompat(enc)) {
	len += 19;		/* ".force_encoding('')" */
	len += strlen(enc->name);
    }

    result = rb_str_new5(str, 0, len);
    p = RSTRING_PTR(str); pend = p + RSTRING_LEN(str);
    q = RSTRING_PTR(result); qend = q + len + 1;

    *q++ = '"';
    while (p < pend) {
	unsigned char c = *p++;

	if (c == '"' || c == '\\') {
	    *q++ = '\\';
	    *q++ = c;
	}
	else if (c == '#') {
	    if (IS_EVSTR(p, pend)) *q++ = '\\';
	    *q++ = '#';
	}
	else if (c == '\n') {
	    *q++ = '\\';
	    *q++ = 'n';
	}
	else if (c == '\r') {
	    *q++ = '\\';
	    *q++ = 'r';
	}
	else if (c == '\t') {
	    *q++ = '\\';
	    *q++ = 't';
	}
	else if (c == '\f') {
	    *q++ = '\\';
	    *q++ = 'f';
	}
	else if (c == '\013') {
	    *q++ = '\\';
	    *q++ = 'v';
	}
	else if (c == '\010') {
	    *q++ = '\\';
	    *q++ = 'b';
	}
	else if (c == '\007') {
	    *q++ = '\\';
	    *q++ = 'a';
	}
	else if (c == '\033') {
	    *q++ = '\\';
	    *q++ = 'e';
	}
	else if (ISPRINT(c)) {
	    *q++ = c;
	}
	else {
	    *q++ = '\\';
	    if (u8) {
		int n = rb_enc_precise_mbclen(p-1, pend, enc) - 1;
		if (MBCLEN_CHARFOUND_P(n)) {
		    int cc = rb_enc_mbc_to_codepoint(p-1, pend, enc);
		    p += n;
		    snprintf(q, qend-q, "u{%x}", cc);
		    q += strlen(q);
		    continue;
		}
	    }
	    snprintf(q, qend-q, "x%02X", c);
	    q += 3;
	}
    }
    *q++ = '"';
    *q = '\0';
    if (!rb_enc_asciicompat(enc)) {
	snprintf(q, qend-q, ".force_encoding(\"%s\")", enc->name);
	enc = rb_ascii8bit_encoding();
    }
    OBJ_INFECT(result, str);
    /* result from dump is ASCII */
    rb_enc_associate(result, enc);
    ENC_CODERANGE_SET(result, ENC_CODERANGE_7BIT);
    return result;
}

#each_byte {|fixnum| ... } ⇒ `String` #each_byte ⇒ `Object`

Passes each byte in str to the given block, or returns an enumerator if no block is given.

"hello".each_byte {|c| print c, ' ' }

produces:

104 101 108 108 111

Overloads:

#each_byte {|fixnum| ... } ⇒ String
Yields:
- (fixnum)
Returns:
- (String)

# File 'string.c', line 6651

static VALUE
rb_str_each_byte(VALUE str)
{
    return rb_str_enumerate_bytes(str, 0);
}

#each_char {|cstr| ... } ⇒ `String` #each_char ⇒ `Object`

Passes each character in str to the given block, or returns an enumerator if no block is given.

"hello".each_char {|c| print c, ' ' }

produces:

h e l l o

Overloads:

#each_char {|cstr| ... } ⇒ String
Yields:
- (cstr)
Returns:
- (String)

# File 'string.c', line 6757

static VALUE
rb_str_each_char(VALUE str)
{
    return rb_str_enumerate_chars(str, 0);
}

#each_codepoint {|integer| ... } ⇒ `String` #each_codepoint ⇒ `Object`

Passes the Integer ordinal of each character in str, also known as a codepoint when applied to Unicode strings to the given block.

If no block is given, an enumerator is returned instead.

"hello\u0639".each_codepoint {|c| print c, ' ' }

produces:

104 101 108 108 111 1593

Overloads:

#each_codepoint {|integer| ... } ⇒ String
Yields:
- (integer)
Returns:
- (String)

# File 'string.c', line 6850

static VALUE
rb_str_each_codepoint(VALUE str)
{
    return rb_str_enumerate_codepoints(str, 0);
}

#each_line(separator = $/) {|substr| ... } ⇒ `String` #each_line(separator = $/) ⇒ `Object`

Splits str using the supplied parameter as the record separator ($/ by default), passing each substring in turn to the supplied block. If a zero-length record separator is supplied, the string is split into paragraphs delimited by multiple successive newlines.

If no block is given, an enumerator is returned instead.

print "Example one\n"
"hello\nworld".each_line {|s| p s}
print "Example two\n"
"hello\nworld".each_line('l') {|s| p s}
print "Example three\n"
"hello\n\n\nworld".each_line('') {|s| p s}

produces:

Example one
"hello\n"
"world"
Example two
"hel"
"l"
"o\nworl"
"d"
Example three
"hello\n\n\n"
"world"

Overloads:

#each_line(separator = $/) {|substr| ... } ⇒ String
Yields:
- (substr)
Returns:
- (String)

# File 'string.c', line 6570

static VALUE
rb_str_each_line(int argc, VALUE *argv, VALUE str)
{
    return rb_str_enumerate_lines(argc, argv, str, 0);
}

#empty? ⇒ `Boolean`

Returns true if str has a length of zero.

"hello".empty?   #=> false
" ".empty?       #=> false
"".empty?        #=> true

Returns:

(Boolean)

Returns:

(Boolean)

# File 'string.c', line 1333

static VALUE
rb_str_empty(VALUE str)
{
    if (RSTRING_LEN(str) == 0)
	return Qtrue;
    return Qfalse;
}

#encode(encoding[, options]) ⇒ `String` #encode(dst_encoding, src_encoding[, options]) ⇒ `String` #encode([options]) ⇒ `String`

The first form returns a copy of str transcoded to encoding encoding. The second form returns a copy of str transcoded from src_encoding to dst_encoding. The last form returns a copy of str transcoded to Encoding.default_internal.

By default, the first and second form raise Encoding::UndefinedConversionError for characters that are undefined in the destination encoding, and Encoding::InvalidByteSequenceError for invalid byte sequences in the source encoding. The last form by default does not raise exceptions but uses replacement strings.

The options Hash gives details for conversion and can have the following keys:

:invalid: If the value is :replace, #encode replaces invalid byte sequences in str with the replacement character. The default is to raise the Encoding::InvalidByteSequenceError exception
:undef: If the value is :replace, #encode replaces characters which are undefined in the destination encoding with the replacement character. The default is to raise the Encoding::UndefinedConversionError.
:replace: Sets the replacement string to the given value. The default replacement string is “uFFFD” for Unicode encoding forms, and “?” otherwise.
:fallback: Sets the replacement string by the given object for undefined character. The object should be a Hash, a Proc, a Method, or an object which has [] method. Its key is an undefined character encoded in the source encoding of current transcoder. Its value can be any encoding until it can be converted into the destination encoding of the transcoder.
:xml: The value must be :text or :attr. If the value is :text #encode replaces undefined characters with their (upper-case hexadecimal) numeric character references. ‘&’, ‘<’, and ‘>’ are converted to “&”, “<”, and “>”, respectively. If the value is :attr, #encode also quotes the replacement result (using ‘“’), and replaces ‘”’ with “"”.
:cr_newline: Replaces LF (“n”) with CR (“r”) if value is true.
:crlf_newline: Replaces LF (“n”) with CRLF (“rn”) if value is true.
:universal_newline: Replaces CRLF (“rn”) and CR (“r”) with LF (“n”) if value is true.

Overloads:

#encode(encoding[, options]) ⇒ String
Returns:
- (String)
#encode(dst_encoding, src_encoding[, options]) ⇒ String
Returns:
- (String)
#encode([options]) ⇒ String
Returns:
- (String)

# File 'transcode.c', line 2876

static VALUE
str_encode(int argc, VALUE *argv, VALUE str)
{
    VALUE newstr = str;
    int encidx = str_transcode(argc, argv, &newstr);
    return encoded_dup(newstr, str, encidx);
}

#encode!(encoding[, options]) ⇒ `String` #encode!(dst_encoding, src_encoding[, options]) ⇒ `String`

The first form transcodes the contents of str from str.encoding to encoding. The second form transcodes the contents of str from src_encoding to dst_encoding. The options Hash gives details for conversion. See String#encode for details. Returns the string even if no changes were made.

Overloads:

#encode!(encoding[, options]) ⇒ String
Returns:
- (String)
#encode!(dst_encoding, src_encoding[, options]) ⇒ String
Returns:
- (String)

# File 'transcode.c', line 2798

static VALUE
str_encode_bang(int argc, VALUE *argv, VALUE str)
{
    VALUE newstr;
    int encidx;

    rb_check_frozen(str);

    newstr = str;
    encidx = str_transcode(argc, argv, &newstr);

    if (encidx < 0) return str;
    if (newstr == str) {
	rb_enc_associate_index(str, encidx);
	return str;
    }
    rb_str_shared_replace(str, newstr);
    return str_encode_associate(str, encidx);
}

#encoding ⇒ `Encoding`

Returns the Encoding object that represents the encoding of obj.

Returns:

(Encoding)

# File 'encoding.c', line 929

VALUE
rb_obj_encoding(VALUE obj)
{
    int idx = rb_enc_get_index(obj);
    if (idx < 0) {
	rb_raise(rb_eTypeError, "unknown encoding");
    }
    return rb_enc_from_encoding_index(idx & ENC_INDEX_MASK);
}

#end_with?([suffixes]) ⇒ `Boolean`

Returns true if str ends with one of the suffixes given.

Returns:

(Boolean)

Returns:

(Boolean)

# File 'string.c', line 7854

static VALUE
rb_str_end_with(int argc, VALUE *argv, VALUE str)
{
    int i;
    char *p, *s, *e;
    rb_encoding *enc;

    for (i=0; i<argc; i++) {
	VALUE tmp = argv[i];
	StringValue(tmp);
	enc = rb_enc_check(str, tmp);
	if (RSTRING_LEN(str) < RSTRING_LEN(tmp)) continue;
	p = RSTRING_PTR(str);
        e = p + RSTRING_LEN(str);
	s = e - RSTRING_LEN(tmp);
	if (rb_enc_left_char_head(p, s, e, enc) != s)
	    continue;
	if (memcmp(s, RSTRING_PTR(tmp), RSTRING_LEN(tmp)) == 0)
	    return Qtrue;
    }
    return Qfalse;
}

#eql?(other) ⇒ `Boolean`

Two strings are equal if they have the same length and content.

Returns:

(Boolean)

Returns:

(Boolean)

# File 'string.c', line 2562

static VALUE
rb_str_eql(VALUE str1, VALUE str2)
{
    if (str1 == str2) return Qtrue;
    if (!RB_TYPE_P(str2, T_STRING)) return Qfalse;
    return str_eql(str1, str2);
}

#force_encoding(encoding) ⇒ `String`

Changes the encoding to encoding and returns self.

Returns:

(String)

# File 'string.c', line 7894

static VALUE
rb_str_force_encoding(VALUE str, VALUE enc)
{
    str_modifiable(str);
    rb_enc_associate(str, rb_to_encoding(enc));
    ENC_CODERANGE_CLEAR(str);
    return str;
}

#freeze ⇒ `Object`

#getbyte(index) ⇒ `0 .. 255`

returns the indexth byte as an integer.

Returns:

(0 .. 255)

# File 'string.c', line 4370

static VALUE
rb_str_getbyte(VALUE str, VALUE index)
{
    long pos = NUM2LONG(index);

    if (pos < 0)
        pos += RSTRING_LEN(str);
    if (pos < 0 ||  RSTRING_LEN(str) <= pos)
        return Qnil;

    return INT2FIX((unsigned char)RSTRING_PTR(str)[pos]);
}

#gsub(pattern, replacement) ⇒ `String` #gsub(pattern, hash) ⇒ `String` #gsub(pattern) {|match| ... } ⇒ `String` #gsub(pattern) ⇒ `Object`

Returns a copy of str with the all occurrences of pattern substituted for the second argument. The pattern is typically a Regexp; if given as a String, any regular expression metacharacters it contains will be interpreted literally, e.g. '\\d' will match a backlash followed by ‘d’, instead of a digit.

If replacement is a String it will be substituted for the matched text. It may contain back-references to the pattern’s capture groups of the form \\d, where d is a group number, or \\k<n>, where n is a group name. If it is a double-quoted string, both back-references must be preceded by an additional backslash. However, within replacement the special match variables, such as $&, will not refer to the current match.

If the second argument is a Hash, and the matched text is one of its keys, the corresponding value is the replacement string.

In the block form, the current match string is passed in as a parameter, and variables such as $1, $2, $`, $&, and $' will be set appropriately. The value returned by the block will be substituted for the match on each call.

The result inherits any tainting in the original string or any supplied replacement string.

When neither a block nor a second argument is supplied, an Enumerator is returned.

"hello".gsub(/[aeiou]/, '*')                  #=> "h*ll*"
"hello".gsub(/([aeiou])/, '<\1>')             #=> "h<e>ll<o>"
"hello".gsub(/./) {|s| s.ord.to_s + ' '}      #=> "104 101 108 108 111 "
"hello".gsub(/(?<foo>[aeiou])/, '{\k<foo>}')  #=> "h{e}ll{o}"
'hello'.gsub(/[eo]/, 'e' => 3, 'o' => '*')    #=> "h3ll*"

Overloads:

#gsub(pattern, replacement) ⇒ String
Returns:
- (String)
#gsub(pattern, hash) ⇒ String
Returns:
- (String)
#gsub(pattern) {|match| ... } ⇒ String
Yields:
- (match)
Returns:
- (String)

# File 'string.c', line 4295

static VALUE
rb_str_gsub(int argc, VALUE *argv, VALUE str)
{
    return str_gsub(argc, argv, str, 0);
}

#gsub!(pattern, replacement) ⇒ `String`^? #gsub!(pattern) {|match| ... } ⇒ `String`^? #gsub!(pattern) ⇒ `Object`

Performs the substitutions of String#gsub in place, returning str, or nil if no substitutions were performed. If no block and no replacement is given, an enumerator is returned instead.

Overloads:

#gsub!(pattern, replacement) ⇒ String^?
Returns:
- (String, nil)
#gsub!(pattern) {|match| ... } ⇒ String^?
Yields:
- (match)
Returns:
- (String, nil)

# File 'string.c', line 4244

static VALUE
rb_str_gsub_bang(int argc, VALUE *argv, VALUE str)
{
    str_modify_keep_cr(str);
    return str_gsub(argc, argv, str, 1);
}

#hash ⇒ `Fixnum`

Return a hash based on the string’s length and content.

Returns:

(Fixnum)

# File 'string.c', line 2451

static VALUE
rb_str_hash_m(VALUE str)
{
    st_index_t hval = rb_str_hash(str);
    return INT2FIX(hval);
}

#hex ⇒ `Integer`

Treats leading characters from str as a string of hexadecimal digits (with an optional sign and an optional 0x) and returns the corresponding number. Zero is returned on error.

"0x0a".hex     #=> 10
"-1234".hex    #=> -4660
"0".hex        #=> 0
"wombat".hex   #=> 0

Returns:

(Integer)

# File 'string.c', line 7367

static VALUE
rb_str_hex(VALUE str)
{
    return rb_str_to_inum(str, 16, FALSE);
}

#include?(other_str) ⇒ `Boolean`

Returns true if str contains the given string or character.

"hello".include? "lo"   #=> true
"hello".include? "ol"   #=> false
"hello".include? ?h     #=> true

Returns:

(Boolean)

Returns:

(Boolean)

# File 'string.c', line 4641

static VALUE
rb_str_include(VALUE str, VALUE arg)
{
    long i;

    StringValue(arg);
    i = rb_str_index(str, arg, 0);

    if (i == -1) return Qfalse;
    return Qtrue;
}

#index(substring[, offset]) ⇒ `Fixnum`^? #index(regexp[, offset]) ⇒ `Fixnum`^?

Returns the index of the first occurrence of the given substring or pattern (regexp) in str. Returns nil if not found. If the second parameter is present, it specifies the position in the string to begin the search.

"hello".index('e')             #=> 1
"hello".index('lo')            #=> 3
"hello".index('a')             #=> nil
"hello".index(?e)              #=> 1
"hello".index(/[aeiou]/, -3)   #=> 4

Overloads:

#index(substring[, offset]) ⇒ Fixnum^?
Returns:
- (Fixnum, nil)
#index(regexp[, offset]) ⇒ Fixnum^?
Returns:
- (Fixnum, nil)

# File 'string.c', line 2747

static VALUE
rb_str_index_m(int argc, VALUE *argv, VALUE str)
{
    VALUE sub;
    VALUE initpos;
    long pos;

    if (rb_scan_args(argc, argv, "11", &sub, &initpos) == 2) {
	pos = NUM2LONG(initpos);
    }
    else {
	pos = 0;
    }
    if (pos < 0) {
	pos += str_strlen(str, STR_ENC_GET(str));
	if (pos < 0) {
	    if (RB_TYPE_P(sub, T_REGEXP)) {
		rb_backref_set(Qnil);
	    }
	    return Qnil;
	}
    }

    if (SPECIAL_CONST_P(sub)) goto generic;
    switch (BUILTIN_TYPE(sub)) {
      case T_REGEXP:
	if (pos > str_strlen(str, STR_ENC_GET(str)))
	    return Qnil;
	pos = str_offset(RSTRING_PTR(str), RSTRING_END(str), pos,
			 rb_enc_check(str, sub), single_byte_optimizable(str));

	pos = rb_reg_search(sub, str, pos, 0);
	pos = rb_str_sublen(str, pos);
	break;

      generic:
      default: {
	VALUE tmp;

	tmp = rb_check_string_type(sub);
	if (NIL_P(tmp)) {
	    rb_raise(rb_eTypeError, "type mismatch: %s given",
		     rb_obj_classname(sub));
	}
	sub = tmp;
      }
	/* fall through */
      case T_STRING:
	pos = rb_str_index(str, sub, pos);
	pos = rb_str_sublen(str, pos);
	break;
    }

    if (pos == -1) return Qnil;
    return LONG2NUM(pos);
}

#replace(other_str) ⇒ `String`

Replaces the contents and taintedness of str with the corresponding values in other_str.

s = "hello"         #=> "hello"
s.replace "world"   #=> "world"

Returns:

(String)

# File 'string.c', line 4313

VALUE
rb_str_replace(VALUE str, VALUE str2)
{
    str_modifiable(str);
    if (str == str2) return str;

    StringValue(str2);
    str_discard(str);
    return str_replace(str, str2);
}

#insert(index, other_str) ⇒ `String`

Inserts other_str before the character at the given index, modifying str. Negative indices count from the end of the string, and insert after the given character. The intent is insert aString so that it starts at the given index.

"abcd".insert(0, 'X')    #=> "Xabcd"
"abcd".insert(3, 'X')    #=> "abcXd"
"abcd".insert(4, 'X')    #=> "abcdX"
"abcd".insert(-3, 'X')   #=> "abXcd"
"abcd".insert(-1, 'X')   #=> "abcdX"

Returns:

(String)

# File 'string.c', line 3882

static VALUE
rb_str_insert(VALUE str, VALUE idx, VALUE str2)
{
    long pos = NUM2LONG(idx);

    if (pos == -1) {
	return rb_str_append(str, str2);
    }
    else if (pos < 0) {
	pos++;
    }
    rb_str_splice(str, pos, 0, str2);
    return str;
}

#inspect ⇒ `String`

Returns a printable version of str, surrounded by quote marks, with special characters escaped.

str = "hello"
str[3] = "\b"
str.inspect       #=> "\"hel\\bo\""

Returns:

(String)

# File 'string.c', line 4791

VALUE
rb_str_inspect(VALUE str)
{
    int encidx = ENCODING_GET(str);
    rb_encoding *enc = rb_enc_from_index(encidx), *actenc;
    const char *p, *pend, *prev;
    char buf[CHAR_ESC_LEN + 1];
    VALUE result = rb_str_buf_new(0);
    rb_encoding *resenc = rb_default_internal_encoding();
    int unicode_p = rb_enc_unicode_p(enc);
    int asciicompat = rb_enc_asciicompat(enc);

    if (resenc == NULL) resenc = rb_default_external_encoding();
    if (!rb_enc_asciicompat(resenc)) resenc = rb_usascii_encoding();
    rb_enc_associate(result, resenc);
    str_buf_cat2(result, "\"");

    p = RSTRING_PTR(str); pend = RSTRING_END(str);
    prev = p;
    actenc = get_actual_encoding(encidx, str);
    if (actenc != enc) {
	enc = actenc;
	if (unicode_p) unicode_p = rb_enc_unicode_p(enc);
    }
    while (p < pend) {
	unsigned int c, cc;
	int n;

        n = rb_enc_precise_mbclen(p, pend, enc);
        if (!MBCLEN_CHARFOUND_P(n)) {
	    if (p > prev) str_buf_cat(result, prev, p - prev);
            n = rb_enc_mbminlen(enc);
            if (pend < p + n)
                n = (int)(pend - p);
            while (n--) {
                snprintf(buf, CHAR_ESC_LEN, "\\x%02X", *p & 0377);
                str_buf_cat(result, buf, strlen(buf));
                prev = ++p;
            }
	    continue;
	}
        n = MBCLEN_CHARFOUND_LEN(n);
	c = rb_enc_mbc_to_codepoint(p, pend, enc);
	p += n;
	if ((asciicompat || unicode_p) &&
	  (c == '"'|| c == '\\' ||
	    (c == '#' &&
             p < pend &&
             MBCLEN_CHARFOUND_P(rb_enc_precise_mbclen(p,pend,enc)) &&
             (cc = rb_enc_codepoint(p,pend,enc),
              (cc == '$' || cc == '@' || cc == '{'))))) {
	    if (p - n > prev) str_buf_cat(result, prev, p - n - prev);
	    str_buf_cat2(result, "\\");
	    if (asciicompat || enc == resenc) {
		prev = p - n;
		continue;
	    }
	}
	switch (c) {
	  case '\n': cc = 'n'; break;
	  case '\r': cc = 'r'; break;
	  case '\t': cc = 't'; break;
	  case '\f': cc = 'f'; break;
	  case '\013': cc = 'v'; break;
	  case '\010': cc = 'b'; break;
	  case '\007': cc = 'a'; break;
	  case 033: cc = 'e'; break;
	  default: cc = 0; break;
	}
	if (cc) {
	    if (p - n > prev) str_buf_cat(result, prev, p - n - prev);
	    buf[0] = '\\';
	    buf[1] = (char)cc;
	    str_buf_cat(result, buf, 2);
	    prev = p;
	    continue;
	}
	if ((enc == resenc && rb_enc_isprint(c, enc)) ||
	    (asciicompat && rb_enc_isascii(c, enc) && ISPRINT(c))) {
	    continue;
	}
	else {
	    if (p - n > prev) str_buf_cat(result, prev, p - n - prev);
	    rb_str_buf_cat_escaped_char(result, c, unicode_p);
	    prev = p;
	    continue;
	}
    }
    if (p > prev) str_buf_cat(result, prev, p - prev);
    str_buf_cat2(result, "\"");

    OBJ_INFECT(result, str);
    return result;
}

#intern ⇒ `Object` #to_sym ⇒ `Object`

Returns the Symbol corresponding to str, creating the symbol if it did not previously exist. See Symbol#id2name.

"Koala".intern         #=> :Koala
s = 'cat'.to_sym       #=> :cat
s == :cat              #=> true
s = '@cat'.to_sym      #=> :@cat
s == :@cat             #=> true

This can also be used to create symbols that cannot be represented using the :xxx notation.

'cat and dog'.to_sym   #=> :"cat and dog"

# File 'string.c', line 7469

VALUE
rb_str_intern(VALUE s)
{
    VALUE str = RB_GC_GUARD(s);
    ID id;

    id = rb_intern_str(str);
    return ID2SYM(id);
}

#length ⇒ `Integer` #size ⇒ `Integer`

Returns the character length of str.

Overloads:

#length ⇒ Integer
Returns:
- (Integer)
#size ⇒ Integer
Returns:
- (Integer)

# File 'string.c', line 1297

VALUE
rb_str_length(VALUE str)
{
    long len;

    len = str_strlen(str, STR_ENC_GET(str));
    return LONG2NUM(len);
}

#lines(separator = $/) ⇒ `Array`

Returns an array of lines in str split using the supplied record separator ($/ by default). This is a shorthand for str.each_line(separator).to_a.

If a block is given, which is a deprecated form, works the same as each_line.

Returns:

(Array)

# File 'string.c', line 6588

static VALUE
rb_str_lines(int argc, VALUE *argv, VALUE str)
{
    return rb_str_enumerate_lines(argc, argv, str, 1);
}

#ljust(integer, padstr = ' ') ⇒ `String`

If integer is greater than the length of str, returns a new String of length integer with str left justified and padded with padstr; otherwise, returns str.

"hello".ljust(4)            #=> "hello"
"hello".ljust(20)           #=> "hello               "
"hello".ljust(20, '1234')   #=> "hello123412341234123"

Returns:

(String)

# File 'string.c', line 7670

static VALUE
rb_str_ljust(int argc, VALUE *argv, VALUE str)
{
    return rb_str_justify(argc, argv, str, 'l');
}

#lstrip ⇒ `String`

Returns a copy of str with leading whitespace removed. See also String#rstrip and String#strip.

"  hello  ".lstrip   #=> "hello  "
"hello".lstrip       #=> "hello"

Returns:

(String)

# File 'string.c', line 7136

static VALUE
rb_str_lstrip(VALUE str)
{
    str = rb_str_dup(str);
    rb_str_lstrip_bang(str);
    return str;
}

#lstrip! ⇒ `self`^?

Removes leading whitespace from str, returning nil if no change was made. See also String#rstrip! and String#strip!.

"  hello  ".lstrip   #=> "hello  "
"hello".lstrip!      #=> nil

Returns:

(self, nil)

# File 'string.c', line 7095

static VALUE
rb_str_lstrip_bang(VALUE str)
{
    rb_encoding *enc;
    char *s, *t, *e;

    str_modify_keep_cr(str);
    enc = STR_ENC_GET(str);
    s = RSTRING_PTR(str);
    if (!s || RSTRING_LEN(str) == 0) return Qnil;
    e = t = RSTRING_END(str);
    /* remove spaces at head */
    while (s < e) {
	int n;
	unsigned int cc = rb_enc_codepoint_len(s, e, &n, enc);

	if (!rb_isspace(cc)) break;
	s += n;
    }

    if (s > RSTRING_PTR(str)) {
	STR_SET_LEN(str, t-s);
	memmove(RSTRING_PTR(str), s, RSTRING_LEN(str));
	RSTRING_PTR(str)[RSTRING_LEN(str)] = '\0';
	return str;
    }
    return Qnil;
}

#match(pattern) ⇒ `MatchData`^? #match(pattern, pos) ⇒ `MatchData`^?

Converts pattern to a Regexp (if it isn’t already one), then invokes its match method on str. If the second parameter is present, it specifies the position in the string to begin the search.

'hello'.match('(.)\1')      #=> #<MatchData "ll" 1:"l">
'hello'.match('(.)\1')[0]   #=> "ll"
'hello'.match(/(.)\1/)[0]   #=> "ll"
'hello'.match('xx')         #=> nil

If a block is given, invoke the block with MatchData if match succeed, so that you can write

str.match(pat) {|m| ...}

instead of

if m = str.match(pat)
  ...
end

The return value is a value from block execution in this case.

Overloads:

#match(pattern) ⇒ MatchData^?
Returns:
- (MatchData, nil)
#match(pattern, pos) ⇒ MatchData^?
Returns:
- (MatchData, nil)

# File 'string.c', line 3039

static VALUE
rb_str_match_m(int argc, VALUE *argv, VALUE str)
{
    VALUE re, result;
    if (argc < 1)
	rb_check_arity(argc, 1, 2);
    re = argv[0];
    argv[0] = str;
    result = rb_funcall2(get_pat(re, 0), rb_intern("match"), argc, argv);
    if (!NIL_P(result) && rb_block_given_p()) {
	return rb_yield(result);
    }
    return result;
}

#succ ⇒ `String` #next ⇒ `String`

Returns the successor to str. The successor is calculated by incrementing characters starting from the rightmost alphanumeric (or the rightmost character if there are no alphanumerics) in the string. Incrementing a digit always results in another digit, and incrementing a letter results in another letter of the same case. Incrementing nonalphanumerics uses the underlying character set’s collating sequence.

If the increment generates a “carry,” the character to the left of it is incremented. This process repeats until there is no carry, adding an additional character if necessary.

"abcd".succ        #=> "abce"
"THX1138".succ     #=> "THX1139"
"<<koala>>".succ   #=> "<<koalb>>"
"1999zzz".succ     #=> "2000aaa"
"ZZZ9999".succ     #=> "AAAA0000"
"***".succ         #=> "**+"

Overloads:

#succ ⇒ String
Returns:
- (String)
#next ⇒ String
Returns:
- (String)

# File 'string.c', line 3256

VALUE
rb_str_succ(VALUE orig)
{
    rb_encoding *enc;
    VALUE str;
    char *sbeg, *s, *e, *last_alnum = 0;
    int c = -1;
    long l;
    char carry[ONIGENC_CODE_TO_MBC_MAXLEN] = "\1";
    long carry_pos = 0, carry_len = 1;
    enum neighbor_char neighbor = NEIGHBOR_FOUND;

    str = rb_str_new5(orig, RSTRING_PTR(orig), RSTRING_LEN(orig));
    rb_enc_cr_str_copy_for_substr(str, orig);
    OBJ_INFECT(str, orig);
    if (RSTRING_LEN(str) == 0) return str;

    enc = STR_ENC_GET(orig);
    sbeg = RSTRING_PTR(str);
    s = e = sbeg + RSTRING_LEN(str);

    while ((s = rb_enc_prev_char(sbeg, s, e, enc)) != 0) {
	if (neighbor == NEIGHBOR_NOT_CHAR && last_alnum) {
	    if (ISALPHA(*last_alnum) ? ISDIGIT(*s) :
		ISDIGIT(*last_alnum) ? ISALPHA(*s) : 0) {
		s = last_alnum;
		break;
	    }
	}
	l = rb_enc_precise_mbclen(s, e, enc);
	if (!ONIGENC_MBCLEN_CHARFOUND_P(l)) continue;
	l = ONIGENC_MBCLEN_CHARFOUND_LEN(l);
        neighbor = enc_succ_alnum_char(s, l, enc, carry);
        switch (neighbor) {
	  case NEIGHBOR_NOT_CHAR:
	    continue;
	  case NEIGHBOR_FOUND:
	    return str;
	  case NEIGHBOR_WRAPPED:
	    last_alnum = s;
	    break;
	}
        c = 1;
        carry_pos = s - sbeg;
        carry_len = l;
    }
    if (c == -1) {		/* str contains no alnum */
	s = e;
	while ((s = rb_enc_prev_char(sbeg, s, e, enc)) != 0) {
            enum neighbor_char neighbor;
	    char tmp[ONIGENC_CODE_TO_MBC_MAXLEN];
	    l = rb_enc_precise_mbclen(s, e, enc);
	    if (!ONIGENC_MBCLEN_CHARFOUND_P(l)) continue;
	    l = ONIGENC_MBCLEN_CHARFOUND_LEN(l);
	    MEMCPY(tmp, s, char, l);
	    neighbor = enc_succ_char(tmp, l, enc);
	    switch (neighbor) {
	      case NEIGHBOR_FOUND:
		MEMCPY(s, tmp, char, l);
                return str;
		break;
	      case NEIGHBOR_WRAPPED:
		MEMCPY(s, tmp, char, l);
		break;
	      case NEIGHBOR_NOT_CHAR:
		break;
	    }
            if (rb_enc_precise_mbclen(s, s+l, enc) != l) {
                /* wrapped to \0...\0.  search next valid char. */
                enc_succ_char(s, l, enc);
            }
            if (!rb_enc_asciicompat(enc)) {
                MEMCPY(carry, s, char, l);
                carry_len = l;
            }
            carry_pos = s - sbeg;
	}
    }
    RESIZE_CAPA(str, RSTRING_LEN(str) + carry_len);
    s = RSTRING_PTR(str) + carry_pos;
    memmove(s + carry_len, s, RSTRING_LEN(str) - carry_pos);
    memmove(s, carry, carry_len);
    STR_SET_LEN(str, RSTRING_LEN(str) + carry_len);
    RSTRING_PTR(str)[RSTRING_LEN(str)] = '\0';
    rb_enc_str_coderange(str);
    return str;
}

#succ! ⇒ `String` #next! ⇒ `String`

Equivalent to String#succ, but modifies the receiver in place.

Overloads:

#succ! ⇒ String
Returns:
- (String)
#next! ⇒ String
Returns:
- (String)

# File 'string.c', line 3354

static VALUE
rb_str_succ_bang(VALUE str)
{
    rb_str_shared_replace(str, rb_str_succ(str));

    return str;
}

#oct ⇒ `Integer`

Treats leading characters of str as a string of octal digits (with an optional sign) and returns the corresponding number. Returns 0 if the conversion fails.

"123".oct       #=> 83
"-377".oct      #=> -255
"bad".oct       #=> 0
"0377bad".oct   #=> 255

Returns:

(Integer)

# File 'string.c', line 7388

static VALUE
rb_str_oct(VALUE str)
{
    return rb_str_to_inum(str, -8, FALSE);
}

#ord ⇒ `Integer`

Return the Integer ordinal of a one-character string.

"a".ord         #=> 97

Returns:

(Integer)

# File 'string.c', line 7489

VALUE
rb_str_ord(VALUE s)
{
    unsigned int c;

    c = rb_enc_codepoint(RSTRING_PTR(s), RSTRING_END(s), STR_ENC_GET(s));
    return UINT2NUM(c);
}

#partition(sep) ⇒ `Array` #partition(regexp) ⇒ `Array`

Searches sep or pattern (regexp) in the string and returns the part before it, the match, and the part after it. If it is not found, returns two empty strings and str.

"hello".partition("l")         #=> ["he", "l", "lo"]
"hello".partition("x")         #=> ["hello", "", ""]
"hello".partition(/.l/)        #=> ["h", "el", "lo"]

Overloads:

#partition(sep) ⇒ Array
Returns:
- (Array)
#partition(regexp) ⇒ Array
Returns:
- (Array)

# File 'string.c', line 7731

static VALUE
rb_str_partition(VALUE str, VALUE sep)
{
    long pos;
    int regex = FALSE;

    if (RB_TYPE_P(sep, T_REGEXP)) {
	pos = rb_reg_search(sep, str, 0, 0);
	regex = TRUE;
    }
    else {
	VALUE tmp;

	tmp = rb_check_string_type(sep);
	if (NIL_P(tmp)) {
	    rb_raise(rb_eTypeError, "type mismatch: %s given",
		     rb_obj_classname(sep));
	}
	sep = tmp;
	pos = rb_str_index(str, sep, 0);
    }
    if (pos < 0) {
      failed:
	return rb_ary_new3(3, str, str_new_empty(str), str_new_empty(str));
    }
    if (regex) {
	sep = rb_str_subpat(str, sep, INT2FIX(0));
	if (pos == 0 && RSTRING_LEN(sep) == 0) goto failed;
    }
    return rb_ary_new3(3, rb_str_subseq(str, 0, pos),
		          sep,
		          rb_str_subseq(str, pos+RSTRING_LEN(sep),
					     RSTRING_LEN(str)-pos-RSTRING_LEN(sep)));
}

#prepend(other_str) ⇒ `String`

Prepend—Prepend the given string to str.

a = "world"
a.prepend("hello ") #=> "hello world"
a                   #=> "hello world"

Returns:

(String)

# File 'string.c', line 2412

static VALUE
rb_str_prepend(VALUE str, VALUE str2)
{
    StringValue(str2);
    StringValue(str);
    rb_str_update(str, 0L, 0L, str2);
    return str;
}

#replace(other_str) ⇒ `String`

Replaces the contents and taintedness of str with the corresponding values in other_str.

s = "hello"         #=> "hello"
s.replace "world"   #=> "world"

Returns:

(String)

# File 'string.c', line 4313

VALUE
rb_str_replace(VALUE str, VALUE str2)
{
    str_modifiable(str);
    if (str == str2) return str;

    StringValue(str2);
    str_discard(str);
    return str_replace(str, str2);
}

#reverse ⇒ `String`

Returns a new string with the characters from str in reverse order.

"stressed".reverse   #=> "desserts"

Returns:

(String)

# File 'string.c', line 4538

static VALUE
rb_str_reverse(VALUE str)
{
    rb_encoding *enc;
    VALUE rev;
    char *s, *e, *p;
    int single = 1;

    if (RSTRING_LEN(str) <= 1) return rb_str_dup(str);
    enc = STR_ENC_GET(str);
    rev = rb_str_new5(str, 0, RSTRING_LEN(str));
    s = RSTRING_PTR(str); e = RSTRING_END(str);
    p = RSTRING_END(rev);

    if (RSTRING_LEN(str) > 1) {
	if (single_byte_optimizable(str)) {
	    while (s < e) {
		*--p = *s++;
	    }
	}
	else if (ENC_CODERANGE(str) == ENC_CODERANGE_VALID) {
	    while (s < e) {
		int clen = rb_enc_fast_mbclen(s, e, enc);

		if (clen > 1 || (*s & 0x80)) single = 0;
		p -= clen;
		memcpy(p, s, clen);
		s += clen;
	    }
	}
	else {
	    while (s < e) {
		int clen = rb_enc_mbclen(s, e, enc);

		if (clen > 1 || (*s & 0x80)) single = 0;
		p -= clen;
		memcpy(p, s, clen);
		s += clen;
	    }
	}
    }
    STR_SET_LEN(rev, RSTRING_LEN(str));
    OBJ_INFECT(rev, str);
    if (ENC_CODERANGE(str) == ENC_CODERANGE_UNKNOWN) {
	if (single) {
	    ENC_CODERANGE_SET(str, ENC_CODERANGE_7BIT);
	}
	else {
	    ENC_CODERANGE_SET(str, ENC_CODERANGE_VALID);
	}
    }
    rb_enc_cr_str_copy_for_substr(rev, str);

    return rev;
}

#reverse! ⇒ `String`

Reverses str in place.

Returns:

(String)

# File 'string.c', line 4602

static VALUE
rb_str_reverse_bang(VALUE str)
{
    if (RSTRING_LEN(str) > 1) {
	if (single_byte_optimizable(str)) {
	    char *s, *e, c;

	    str_modify_keep_cr(str);
	    s = RSTRING_PTR(str);
	    e = RSTRING_END(str) - 1;
	    while (s < e) {
		c = *s;
		*s++ = *e;
		*e-- = c;
	    }
	}
	else {
	    rb_str_shared_replace(str, rb_str_reverse(str));
	}
    }
    else {
	str_modify_keep_cr(str);
    }
    return str;
}

#rindex(substring[, fixnum]) ⇒ `Fixnum`^? #rindex(regexp[, fixnum]) ⇒ `Fixnum`^?

Returns the index of the last occurrence of the given substring or pattern (regexp) in str. Returns nil if not found. If the second parameter is present, it specifies the position in the string to end the search—characters beyond this point will not be considered.

"hello".rindex('e')             #=> 1
"hello".rindex('l')             #=> 3
"hello".rindex('a')             #=> nil
"hello".rindex(?e)              #=> 1
"hello".rindex(/[aeiou]/, -2)   #=> 1

Overloads:

#rindex(substring[, fixnum]) ⇒ Fixnum^?
Returns:
- (Fixnum, nil)
#rindex(regexp[, fixnum]) ⇒ Fixnum^?
Returns:
- (Fixnum, nil)

# File 'string.c', line 2912

static VALUE
rb_str_rindex_m(int argc, VALUE *argv, VALUE str)
{
    VALUE sub;
    VALUE vpos;
    rb_encoding *enc = STR_ENC_GET(str);
    long pos, len = str_strlen(str, enc);

    if (rb_scan_args(argc, argv, "11", &sub, &vpos) == 2) {
	pos = NUM2LONG(vpos);
	if (pos < 0) {
	    pos += len;
	    if (pos < 0) {
		if (RB_TYPE_P(sub, T_REGEXP)) {
		    rb_backref_set(Qnil);
		}
		return Qnil;
	    }
	}
	if (pos > len) pos = len;
    }
    else {
	pos = len;
    }

    if (SPECIAL_CONST_P(sub)) goto generic;
    switch (BUILTIN_TYPE(sub)) {
      case T_REGEXP:
	/* enc = rb_get_check(str, sub); */
	pos = str_offset(RSTRING_PTR(str), RSTRING_END(str), pos,
			 STR_ENC_GET(str), single_byte_optimizable(str));

	if (!RREGEXP(sub)->ptr || RREGEXP_SRC_LEN(sub)) {
	    pos = rb_reg_search(sub, str, pos, 1);
	    pos = rb_str_sublen(str, pos);
	}
	if (pos >= 0) return LONG2NUM(pos);
	break;

      generic:
      default: {
	VALUE tmp;

	tmp = rb_check_string_type(sub);
	if (NIL_P(tmp)) {
	    rb_raise(rb_eTypeError, "type mismatch: %s given",
		     rb_obj_classname(sub));
	}
	sub = tmp;
      }
	/* fall through */
      case T_STRING:
	pos = rb_str_rindex(str, sub, pos);
	if (pos >= 0) return LONG2NUM(pos);
	break;
    }
    return Qnil;
}

#rjust(integer, padstr = ' ') ⇒ `String`

If integer is greater than the length of str, returns a new String of length integer with str right justified and padded with padstr; otherwise, returns str.

"hello".rjust(4)            #=> "hello"
"hello".rjust(20)           #=> "               hello"
"hello".rjust(20, '1234')   #=> "123412341234123hello"

Returns:

(String)

# File 'string.c', line 7690

static VALUE
rb_str_rjust(int argc, VALUE *argv, VALUE str)
{
    return rb_str_justify(argc, argv, str, 'r');
}

#rpartition(sep) ⇒ `Array` #rpartition(regexp) ⇒ `Array`

Searches sep or pattern (regexp) in the string from the end of the string, and returns the part before it, the match, and the part after it. If it is not found, returns two empty strings and str.

"hello".rpartition("l")         #=> ["hel", "l", "o"]
"hello".rpartition("x")         #=> ["", "", "hello"]
"hello".rpartition(/.l/)        #=> ["he", "ll", "o"]

Overloads:

#rpartition(sep) ⇒ Array
Returns:
- (Array)
#rpartition(regexp) ⇒ Array
Returns:
- (Array)

# File 'string.c', line 7781

static VALUE
rb_str_rpartition(VALUE str, VALUE sep)
{
    long pos = RSTRING_LEN(str);
    int regex = FALSE;

    if (RB_TYPE_P(sep, T_REGEXP)) {
	pos = rb_reg_search(sep, str, pos, 1);
	regex = TRUE;
    }
    else {
	VALUE tmp;

	tmp = rb_check_string_type(sep);
	if (NIL_P(tmp)) {
	    rb_raise(rb_eTypeError, "type mismatch: %s given",
		     rb_obj_classname(sep));
	}
	sep = tmp;
	pos = rb_str_sublen(str, pos);
	pos = rb_str_rindex(str, sep, pos);
    }
    if (pos < 0) {
	return rb_ary_new3(3, str_new_empty(str), str_new_empty(str), str);
    }
    if (regex) {
	sep = rb_reg_nth_match(0, rb_backref_get());
    }
    else {
	pos = rb_str_offset(str, pos);
    }
    return rb_ary_new3(3, rb_str_subseq(str, 0, pos),
		          sep,
		          rb_str_subseq(str, pos+RSTRING_LEN(sep),
					RSTRING_LEN(str)-pos-RSTRING_LEN(sep)));
}

#rstrip ⇒ `String`

Returns a copy of str with trailing whitespace removed. See also String#lstrip and String#strip.

"  hello  ".rstrip   #=> "  hello"
"hello".rstrip       #=> "hello"

Returns:

(String)

# File 'string.c', line 7206

static VALUE
rb_str_rstrip(VALUE str)
{
    str = rb_str_dup(str);
    rb_str_rstrip_bang(str);
    return str;
}

#rstrip! ⇒ `self`^?

Removes trailing whitespace from str, returning nil if no change was made. See also String#lstrip! and String#strip!.

"  hello  ".rstrip   #=> "  hello"
"hello".rstrip!      #=> nil

Returns:

(self, nil)

# File 'string.c', line 7157

static VALUE
rb_str_rstrip_bang(VALUE str)
{
    rb_encoding *enc;
    char *s, *t, *e;

    str_modify_keep_cr(str);
    enc = STR_ENC_GET(str);
    rb_str_check_dummy_enc(enc);
    s = RSTRING_PTR(str);
    if (!s || RSTRING_LEN(str) == 0) return Qnil;
    t = e = RSTRING_END(str);

    /* remove trailing spaces or '\0's */
    if (single_byte_optimizable(str)) {
	unsigned char c;
	while (s < t && ((c = *(t-1)) == '\0' || ascii_isspace(c))) t--;
    }
    else {
	char *tp;

        while ((tp = rb_enc_prev_char(s, t, e, enc)) != NULL) {
	    unsigned int c = rb_enc_codepoint(tp, e, enc);
	    if (c && !rb_isspace(c)) break;
	    t = tp;
	}
    }
    if (t < e) {
	long len = t-RSTRING_PTR(str);

	STR_SET_LEN(str, len);
	RSTRING_PTR(str)[len] = '\0';
	return str;
    }
    return Qnil;
}

#scan(pattern) ⇒ `Array` #scan(pattern) {|match, ...| ... } ⇒ `String`

Both forms iterate through str, matching the pattern (which may be a Regexp or a String). For each match, a result is generated and either added to the result array or passed to the block. If the pattern contains no groups, each individual result consists of the matched string, $&. If the pattern contains groups, each individual result is itself an array containing one entry per group.

a = "cruel world"
a.scan(/\w+/)        #=> ["cruel", "world"]
a.scan(/.../)        #=> ["cru", "el ", "wor"]
a.scan(/(...)/)      #=> [["cru"], ["el "], ["wor"]]
a.scan(/(..)(..)/)   #=> [["cr", "ue"], ["l ", "wo"]]

And the block form:

a.scan(/\w+/) {|w| print "<<#{w}>> " }
print "\n"
a.scan(/(.)(.)/) {|x,y| print y, x }
print "\n"

produces:

<<cruel>> <<world>>
rceu lowlr

Overloads:

#scan(pattern) ⇒ Array
Returns:
- (Array)
#scan(pattern) {|match, ...| ... } ⇒ String
Yields:
- (match, ...)
Returns:
- (String)

# File 'string.c', line 7321

static VALUE
rb_str_scan(VALUE str, VALUE pat)
{
    VALUE result;
    long start = 0;
    long last = -1, prev = 0;
    char *p = RSTRING_PTR(str); long len = RSTRING_LEN(str);

    pat = get_pat(pat, 1);
    if (!rb_block_given_p()) {
	VALUE ary = rb_ary_new();

	while (!NIL_P(result = scan_once(str, pat, &start))) {
	    last = prev;
	    prev = start;
	    rb_ary_push(ary, result);
	}
	if (last >= 0) rb_reg_search(pat, str, last, 0);
	return ary;
    }

    while (!NIL_P(result = scan_once(str, pat, &start))) {
	last = prev;
	prev = start;
	rb_yield(result);
	str_mod_check(str, p, len);
    }
    if (last >= 0) rb_reg_search(pat, str, last, 0);
    return str;
}

#scrub ⇒ `String` #scrub(repl) ⇒ `String` #scrub {|bytes| ... } ⇒ `String`

If the string is invalid byte sequence then replace invalid bytes with given replacement character, else returns self. If block is given, replace invalid bytes with returned value of the block.

"abc\u3042\x81".scrub #=> "abc\u3042\uFFFD"
"abc\u3042\x81".scrub("*") #=> "abc\u3042*"
"abc\u3042\xE3\x80".scrub{|bytes| '<'+bytes.unpack('H*')[0]+'>' } #=> "abc\u3042<e380>"

Overloads:

#scrub ⇒ String
Returns:
- (String)
#scrub(repl) ⇒ String
Returns:
- (String)
#scrub {|bytes| ... } ⇒ String
Yields:
- (bytes)
Returns:
- (String)

# File 'string.c', line 8289

static VALUE
str_scrub(int argc, VALUE *argv, VALUE str)
{
    VALUE repl = argc ? (rb_check_arity(argc, 0, 1), argv[0]) : Qnil;
    VALUE new = rb_str_scrub(str, repl);
    return NIL_P(new) ? rb_str_dup(str): new;
}

#scrub! ⇒ `String` #scrub!(repl) ⇒ `String` #scrub! {|bytes| ... } ⇒ `String`

If the string is invalid byte sequence then replace invalid bytes with given replacement character, else returns self. If block is given, replace invalid bytes with returned value of the block.

"abc\u3042\x81".scrub! #=> "abc\u3042\uFFFD"
"abc\u3042\x81".scrub!("*") #=> "abc\u3042*"
"abc\u3042\xE3\x80".scrub!{|bytes| '<'+bytes.unpack('H*')[0]+'>' } #=> "abc\u3042<e380>"

Overloads:

#scrub! ⇒ String
Returns:
- (String)
#scrub!(repl) ⇒ String
Returns:
- (String)
#scrub! {|bytes| ... } ⇒ String
Yields:
- (bytes)
Returns:
- (String)

# File 'string.c', line 8311

static VALUE
str_scrub_bang(int argc, VALUE *argv, VALUE str)
{
    VALUE repl = argc ? (rb_check_arity(argc, 0, 1), argv[0]) : Qnil;
    VALUE new = rb_str_scrub(str, repl);
    if (!NIL_P(new)) rb_str_replace(str, new);
    return str;
}

#setbyte(index, integer) ⇒ `Integer`

modifies the indexth byte as integer.

Returns:

(Integer)

# File 'string.c', line 4389

static VALUE
rb_str_setbyte(VALUE str, VALUE index, VALUE value)
{
    long pos = NUM2LONG(index);
    int byte = NUM2INT(value);

    rb_str_modify(str);

    if (pos < -RSTRING_LEN(str) || RSTRING_LEN(str) <= pos)
        rb_raise(rb_eIndexError, "index %ld out of string", pos);
    if (pos < 0)
        pos += RSTRING_LEN(str);

    RSTRING_PTR(str)[pos] = byte;

    return value;
}

#length ⇒ `Integer` #size ⇒ `Integer`

Returns the character length of str.

Overloads:

#length ⇒ Integer
Returns:
- (Integer)
#size ⇒ Integer
Returns:
- (Integer)

# File 'string.c', line 1297

VALUE
rb_str_length(VALUE str)
{
    long len;

    len = str_strlen(str, STR_ENC_GET(str));
    return LONG2NUM(len);
}

#[](index) ⇒ `String`^? #[](start, length) ⇒ `String`^? #[](range) ⇒ `String`^? #[](regexp) ⇒ `String`^? #[](regexp, capture) ⇒ `String`^? #[](match_str) ⇒ `String`^? #slice(index) ⇒ `String`^? #slice(start, length) ⇒ `String`^? #slice(range) ⇒ `String`^? #slice(regexp) ⇒ `String`^? #slice(regexp, capture) ⇒ `String`^? #slice(match_str) ⇒ `String`^?

Returns nil if the initial index falls outside the string or the length is negative.

If a match_str is given, that string is returned if it occurs in the string.

Returns nil if the regular expression does not match or the match string cannot be found.

a = "hello there"

a[1]                   #=> "e"
a[2, 3]                #=> "llo"
a[2..3]                #=> "ll"

a[-3, 2]               #=> "er"
a[7..-2]               #=> "her"
a[-4..-2]              #=> "her"
a[-2..-4]              #=> ""

a[11, 0]               #=> ""
a[11]                  #=> nil
a[12, 0]               #=> nil
a[12..-1]              #=> nil

a[/[aeiou](.)\1/]      #=> "ell"
a[/[aeiou](.)\1/, 0]   #=> "ell"
a[/[aeiou](.)\1/, 1]   #=> "l"
a[/[aeiou](.)\1/, 2]   #=> nil

a[/(?<vowel>[aeiou])(?<non_vowel>[^aeiou])/, "non_vowel"] #=> "l"
a[/(?<vowel>[aeiou])(?<non_vowel>[^aeiou])/, "vowel"]     #=> "e"

a["lo"]                #=> "lo"
a["bye"]               #=> nil

Overloads:

#[](index) ⇒ String^?
Returns:
- (String, nil)
#[](start, length) ⇒ String^?
Returns:
- (String, nil)
#[](range) ⇒ String^?
Returns:
- (String, nil)
#[](regexp) ⇒ String^?
Returns:
- (String, nil)
#[](regexp, capture) ⇒ String^?
Returns:
- (String, nil)
#[](match_str) ⇒ String^?
Returns:
- (String, nil)
#slice(index) ⇒ String^?
Returns:
- (String, nil)
#slice(start, length) ⇒ String^?
Returns:
- (String, nil)
#slice(range) ⇒ String^?
Returns:
- (String, nil)
#slice(regexp) ⇒ String^?
Returns:
- (String, nil)
#slice(regexp, capture) ⇒ String^?
Returns:
- (String, nil)
#slice(match_str) ⇒ String^?
Returns:
- (String, nil)

# File 'string.c', line 3621

static VALUE
rb_str_aref_m(int argc, VALUE *argv, VALUE str)
{
    if (argc == 2) {
	if (RB_TYPE_P(argv[0], T_REGEXP)) {
	    return rb_str_subpat(str, argv[0], argv[1]);
	}
	return rb_str_substr(str, NUM2LONG(argv[0]), NUM2LONG(argv[1]));
    }
    rb_check_arity(argc, 1, 2);
    return rb_str_aref(str, argv[0]);
}

#slice!(fixnum) ⇒ `Fixnum`^? #slice!(fixnum, fixnum) ⇒ `String`^? #slice!(range) ⇒ `String`^? #slice!(regexp) ⇒ `String`^? #slice!(other_str) ⇒ `String`^?

Deletes the specified portion from str, and returns the portion deleted.

string = "this is a string"
string.slice!(2)        #=> "i"
string.slice!(3..6)     #=> " is "
string.slice!(/s.*t/)   #=> "sa st"
string.slice!("r")      #=> "r"
string                  #=> "thing"

Overloads:

#slice!(fixnum) ⇒ Fixnum^?
Returns:
- (Fixnum, nil)
#slice!(fixnum, fixnum) ⇒ String^?
Returns:
- (String, nil)
#slice!(range) ⇒ String^?
Returns:
- (String, nil)
#slice!(regexp) ⇒ String^?
Returns:
- (String, nil)
#slice!(other_str) ⇒ String^?
Returns:
- (String, nil)

# File 'string.c', line 3917

static VALUE
rb_str_slice_bang(int argc, VALUE *argv, VALUE str)
{
    VALUE result;
    VALUE buf[3];
    int i;

    rb_check_arity(argc, 1, 2);
    for (i=0; i<argc; i++) {
	buf[i] = argv[i];
    }
    str_modify_keep_cr(str);
    result = rb_str_aref_m(argc, buf, str);
    if (!NIL_P(result)) {
	buf[i] = rb_str_new(0,0);
	rb_str_aset_m(argc+1, buf, str);
    }
    return result;
}

#split(pattern = $;, [limit]) ⇒ `Array`

Divides str into substrings based on a delimiter, returning an array of these substrings.

If pattern is a String, then its contents are used as the delimiter when splitting str. If pattern is a single space, str is split on whitespace, with leading whitespace and runs of contiguous whitespace characters ignored.

If pattern is a Regexp, str is divided where the pattern matches. Whenever the pattern matches a zero-length string, str is split into individual characters. If pattern contains groups, the respective matches will be returned in the array as well.

If pattern is omitted, the value of $; is used. If $; is nil (which is the default), str is split on whitespace as if ‘ ’ were specified.

If the limit parameter is omitted, trailing null fields are suppressed. If limit is a positive number, at most that number of fields will be returned (if limit is 1, the entire string is returned as the only entry in an array). If negative, there is no limit to the number of fields returned, and trailing null fields are not suppressed.

When the input str is empty an empty Array is returned as the string is considered to have no fields to split.

" now's  the time".split        #=> ["now's", "the", "time"]
" now's  the time".split(' ')   #=> ["now's", "the", "time"]
" now's  the time".split(/ /)   #=> ["", "now's", "", "the", "time"]
"1, 2.34,56, 7".split(%r{,\s*}) #=> ["1", "2.34", "56", "7"]
"hello".split(//)               #=> ["h", "e", "l", "l", "o"]
"hello".split(//, 3)            #=> ["h", "e", "llo"]
"hi mom".split(%r{\s*})         #=> ["h", "i", "m", "o", "m"]

"mellow yellow".split("ello")   #=> ["m", "w y", "w"]
"1,2,,3,4,,".split(',')         #=> ["1", "2", "", "3", "4"]
"1,2,,3,4,,".split(',', 4)      #=> ["1", "2", "", "3,4,,"]
"1,2,,3,4,,".split(',', -4)     #=> ["1", "2", "", "3", "4", "", ""]

"".split(',', -1)               #=> []

Returns:

(Array)

# File 'string.c', line 6195

static VALUE
rb_str_split_m(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    VALUE spat;
    VALUE limit;
    enum {awk, string, regexp} split_type;
    long beg, end, i = 0;
    int lim = 0;
    VALUE result, tmp;

    if (rb_scan_args(argc, argv, "02", &spat, &limit) == 2) {
	lim = NUM2INT(limit);
	if (lim <= 0) limit = Qnil;
	else if (lim == 1) {
	    if (RSTRING_LEN(str) == 0)
		return rb_ary_new2(0);
	    return rb_ary_new3(1, str);
	}
	i = 1;
    }

    enc = STR_ENC_GET(str);
    if (NIL_P(spat)) {
	if (!NIL_P(rb_fs)) {
	    spat = rb_fs;
	    goto fs_set;
	}
	split_type = awk;
    }
    else {
      fs_set:
	if (RB_TYPE_P(spat, T_STRING)) {
	    rb_encoding *enc2 = STR_ENC_GET(spat);

	    split_type = string;
	    if (RSTRING_LEN(spat) == 0) {
		/* Special case - split into chars */
		spat = rb_reg_regcomp(spat);
		split_type = regexp;
	    }
	    else if (rb_enc_asciicompat(enc2) == 1) {
		if (RSTRING_LEN(spat) == 1 && RSTRING_PTR(spat)[0] == ' '){
		    split_type = awk;
		}
	    }
	    else {
		int l;
		if (rb_enc_ascget(RSTRING_PTR(spat), RSTRING_END(spat), &l, enc2) == ' ' &&
		    RSTRING_LEN(spat) == l) {
		    split_type = awk;
		}
	    }
	}
	else {
	    spat = get_pat(spat, 1);
	    split_type = regexp;
	}
    }

    result = rb_ary_new();
    beg = 0;
    if (split_type == awk) {
	char *ptr = RSTRING_PTR(str);
	char *eptr = RSTRING_END(str);
	char *bptr = ptr;
	int skip = 1;
	unsigned int c;

	end = beg;
	if (is_ascii_string(str)) {
	    while (ptr < eptr) {
		c = (unsigned char)*ptr++;
		if (skip) {
		    if (ascii_isspace(c)) {
			beg = ptr - bptr;
		    }
		    else {
			end = ptr - bptr;
			skip = 0;
			if (!NIL_P(limit) && lim <= i) break;
		    }
		}
		else if (ascii_isspace(c)) {
		    rb_ary_push(result, rb_str_subseq(str, beg, end-beg));
		    skip = 1;
		    beg = ptr - bptr;
		    if (!NIL_P(limit)) ++i;
		}
		else {
		    end = ptr - bptr;
		}
	    }
	}
	else {
	    while (ptr < eptr) {
		int n;

		c = rb_enc_codepoint_len(ptr, eptr, &n, enc);
		ptr += n;
		if (skip) {
		    if (rb_isspace(c)) {
			beg = ptr - bptr;
		    }
		    else {
			end = ptr - bptr;
			skip = 0;
			if (!NIL_P(limit) && lim <= i) break;
		    }
		}
		else if (rb_isspace(c)) {
		    rb_ary_push(result, rb_str_subseq(str, beg, end-beg));
		    skip = 1;
		    beg = ptr - bptr;
		    if (!NIL_P(limit)) ++i;
		}
		else {
		    end = ptr - bptr;
		}
	    }
	}
    }
    else if (split_type == string) {
	char *ptr = RSTRING_PTR(str);
	char *temp = ptr;
	char *eptr = RSTRING_END(str);
	char *sptr = RSTRING_PTR(spat);
	long slen = RSTRING_LEN(spat);

	if (is_broken_string(str)) {
	    rb_raise(rb_eArgError, "invalid byte sequence in %s", rb_enc_name(STR_ENC_GET(str)));
	}
	if (is_broken_string(spat)) {
	    rb_raise(rb_eArgError, "invalid byte sequence in %s", rb_enc_name(STR_ENC_GET(spat)));
	}
	enc = rb_enc_check(str, spat);
	while (ptr < eptr &&
	       (end = rb_memsearch(sptr, slen, ptr, eptr - ptr, enc)) >= 0) {
	    /* Check we are at the start of a char */
	    char *t = rb_enc_right_char_head(ptr, ptr + end, eptr, enc);
	    if (t != ptr + end) {
		ptr = t;
		continue;
	    }
	    rb_ary_push(result, rb_str_subseq(str, ptr - temp, end));
	    ptr += end + slen;
	    if (!NIL_P(limit) && lim <= ++i) break;
	}
	beg = ptr - temp;
    }
    else {
	char *ptr = RSTRING_PTR(str);
	long len = RSTRING_LEN(str);
	long start = beg;
	long idx;
	int last_null = 0;
	struct re_registers *regs;

	while ((end = rb_reg_search(spat, str, start, 0)) >= 0) {
	    regs = RMATCH_REGS(rb_backref_get());
	    if (start == end && BEG(0) == END(0)) {
		if (!ptr) {
		    rb_ary_push(result, str_new_empty(str));
		    break;
		}
		else if (last_null == 1) {
		    rb_ary_push(result, rb_str_subseq(str, beg,
						      rb_enc_fast_mbclen(ptr+beg,
									 ptr+len,
									 enc)));
		    beg = start;
		}
		else {
                    if (ptr+start == ptr+len)
                        start++;
                    else
                        start += rb_enc_fast_mbclen(ptr+start,ptr+len,enc);
		    last_null = 1;
		    continue;
		}
	    }
	    else {
		rb_ary_push(result, rb_str_subseq(str, beg, end-beg));
		beg = start = END(0);
	    }
	    last_null = 0;

	    for (idx=1; idx < regs->num_regs; idx++) {
		if (BEG(idx) == -1) continue;
		if (BEG(idx) == END(idx))
		    tmp = str_new_empty(str);
		else
		    tmp = rb_str_subseq(str, BEG(idx), END(idx)-BEG(idx));
		rb_ary_push(result, tmp);
	    }
	    if (!NIL_P(limit) && lim <= ++i) break;
	}
    }
    if (RSTRING_LEN(str) > 0 && (!NIL_P(limit) || RSTRING_LEN(str) > beg || lim < 0)) {
	if (RSTRING_LEN(str) == beg)
	    tmp = str_new_empty(str);
	else
	    tmp = rb_str_subseq(str, beg, RSTRING_LEN(str)-beg);
	rb_ary_push(result, tmp);
    }
    if (NIL_P(limit) && lim == 0) {
	long len;
	while ((len = RARRAY_LEN(result)) > 0 &&
	       (tmp = RARRAY_AREF(result, len-1), RSTRING_LEN(tmp) == 0))
	    rb_ary_pop(result);
    }

    return result;
}

#squeeze([other_str]) ⇒ `String`

Builds a set of characters from the other_str parameter(s) using the procedure described for String#count. Returns a new string where runs of the same character that occur in this set are replaced by a single character. If no arguments are given, all runs of identical characters are replaced by a single character.

"yellow moon".squeeze                  #=> "yelow mon"
"  now   is  the".squeeze(" ")         #=> " now is the"
"putters shoot balls".squeeze("m-z")   #=> "puters shot balls"

Returns:

(String)

# File 'string.c', line 5984

static VALUE
rb_str_squeeze(int argc, VALUE *argv, VALUE str)
{
    str = rb_str_dup(str);
    rb_str_squeeze_bang(argc, argv, str);
    return str;
}

#squeeze!([other_str]) ⇒ `String`^?

Squeezes str in place, returning either str, or nil if no changes were made.

Returns:

(String, nil)

# File 'string.c', line 5894

static VALUE
rb_str_squeeze_bang(int argc, VALUE *argv, VALUE str)
{
    char squeez[TR_TABLE_SIZE];
    rb_encoding *enc = 0;
    VALUE del = 0, nodel = 0;
    char *s, *send, *t;
    int i, modify = 0;
    int ascompat, singlebyte = single_byte_optimizable(str);
    unsigned int save;

    if (argc == 0) {
	enc = STR_ENC_GET(str);
    }
    else {
	for (i=0; i<argc; i++) {
	    VALUE s = argv[i];

	    StringValue(s);
	    enc = rb_enc_check(str, s);
	    if (singlebyte && !single_byte_optimizable(s))
		singlebyte = 0;
	    tr_setup_table(s, squeez, i==0, &del, &nodel, enc);
	}
    }

    str_modify_keep_cr(str);
    s = t = RSTRING_PTR(str);
    if (!s || RSTRING_LEN(str) == 0) return Qnil;
    send = RSTRING_END(str);
    save = -1;
    ascompat = rb_enc_asciicompat(enc);

    if (singlebyte) {
        while (s < send) {
	    unsigned int c = *(unsigned char*)s++;
	    if (c != save || (argc > 0 && !squeez[c])) {
	        *t++ = save = c;
	    }
	}
    } else {
	while (s < send) {
	    unsigned int c;
	    int clen;

	    if (ascompat && (c = *(unsigned char*)s) < 0x80) {
		if (c != save || (argc > 0 && !squeez[c])) {
		    *t++ = save = c;
		}
		s++;
	    }
	    else {
		c = rb_enc_codepoint_len(s, send, &clen, enc);

		if (c != save || (argc > 0 && !tr_find(c, squeez, del, nodel))) {
		    if (t != s) rb_enc_mbcput(c, t, enc);
		    save = c;
		    t += clen;
		}
		s += clen;
	    }
	}
    }

    *t = '\0';
    if (t - RSTRING_PTR(str) != RSTRING_LEN(str)) {
	STR_SET_LEN(str, t - RSTRING_PTR(str));
	modify = 1;
    }

    if (modify) return str;
    return Qnil;
}

#start_with?([prefixes]) ⇒ `Boolean`

Returns true if str starts with one of the prefixes given.

"hello".start_with?("hell")               #=> true

# returns true if one of the prefixes matches.
"hello".start_with?("heaven", "hell")     #=> true
"hello".start_with?("heaven", "paradise") #=> false

Returns:

(Boolean)

Returns:

(Boolean)

# File 'string.c', line 7831

static VALUE
rb_str_start_with(int argc, VALUE *argv, VALUE str)
{
    int i;

    for (i=0; i<argc; i++) {
	VALUE tmp = argv[i];
	StringValue(tmp);
	rb_enc_check(str, tmp);
	if (RSTRING_LEN(str) < RSTRING_LEN(tmp)) continue;
	if (memcmp(RSTRING_PTR(str), RSTRING_PTR(tmp), RSTRING_LEN(tmp)) == 0)
	    return Qtrue;
    }
    return Qfalse;
}

#strip ⇒ `String`

Returns a copy of str with leading and trailing whitespace removed.

"    hello    ".strip   #=> "hello"
"\tgoodbye\r\n".strip   #=> "goodbye"

Returns:

(String)

# File 'string.c', line 7244

static VALUE
rb_str_strip(VALUE str)
{
    str = rb_str_dup(str);
    rb_str_strip_bang(str);
    return str;
}

#strip! ⇒ `String`^?

Removes leading and trailing whitespace from str. Returns nil if str was not altered.

Returns:

(String, nil)

# File 'string.c', line 7223

static VALUE
rb_str_strip_bang(VALUE str)
{
    VALUE l = rb_str_lstrip_bang(str);
    VALUE r = rb_str_rstrip_bang(str);

    if (NIL_P(l) && NIL_P(r)) return Qnil;
    return str;
}

#sub(pattern, replacement) ⇒ `String` #sub(pattern, hash) ⇒ `String` #sub(pattern) {|match| ... } ⇒ `String`

Returns a copy of str with the first occurrence of pattern replaced by the second argument. The pattern is typically a Regexp; if given as a String, any regular expression metacharacters it contains will be interpreted literally, e.g. '\\d' will match a backlash followed by ‘d’, instead of a digit.

If replacement is a String it will be substituted for the matched text. It may contain back-references to the pattern’s capture groups of the form "\d", where d is a group number, or "\k<n>", where n is a group name. If it is a double-quoted string, both back-references must be preceded by an additional backslash. However, within replacement the special match variables, such as &$, will not refer to the current match.

If the second argument is a Hash, and the matched text is one of its keys, the corresponding value is the replacement string.

The result inherits any tainting in the original string or any supplied replacement string.

"hello".sub(/[aeiou]/, '*')                  #=> "h*llo"
"hello".sub(/([aeiou])/, '<\1>')             #=> "h<e>llo"
"hello".sub(/./) {|s| s.ord.to_s + ' ' }     #=> "104 ello"
"hello".sub(/(?<foo>[aeiou])/, '*\k<foo>*')  #=> "h*e*llo"
'Is SHELL your preferred shell?'.sub(/[[:upper:]]{2,}/, ENV)
 #=> "Is /bin/bash your preferred shell?"

Overloads:

#sub(pattern, replacement) ⇒ String
Returns:
- (String)
#sub(pattern, hash) ⇒ String
Returns:
- (String)
#sub(pattern) {|match| ... } ⇒ String
Yields:
- (match)
Returns:
- (String)

# File 'string.c', line 4111

static VALUE
rb_str_sub(int argc, VALUE *argv, VALUE str)
{
    str = rb_str_dup(str);
    rb_str_sub_bang(argc, argv, str);
    return str;
}

#sub!(pattern, replacement) ⇒ `String`^? #sub!(pattern) {|match| ... } ⇒ `String`^?

Performs the same substitution as String#sub in-place.

Returns str if a substitution was performed or nil if no substitution was performed.

Overloads:

#sub!(pattern, replacement) ⇒ String^?
Returns:
- (String, nil)
#sub!(pattern) {|match| ... } ⇒ String^?
Yields:
- (match)
Returns:
- (String, nil)

# File 'string.c', line 3976

static VALUE
rb_str_sub_bang(int argc, VALUE *argv, VALUE str)
{
    VALUE pat, repl, hash = Qnil;
    int iter = 0;
    int tainted = 0;
    long plen;
    int min_arity = rb_block_given_p() ? 1 : 2;

    rb_check_arity(argc, min_arity, 2);
    if (argc == 1) {
	iter = 1;
    }
    else {
	repl = argv[1];
	hash = rb_check_hash_type(argv[1]);
	if (NIL_P(hash)) {
	    StringValue(repl);
	}
	if (OBJ_TAINTED(repl)) tainted = 1;
    }

    pat = get_pat(argv[0], 1);
    str_modifiable(str);
    if (rb_reg_search(pat, str, 0, 0) >= 0) {
	rb_encoding *enc;
	int cr = ENC_CODERANGE(str);
	VALUE match = rb_backref_get();
	struct re_registers *regs = RMATCH_REGS(match);
	long beg0 = BEG(0);
	long end0 = END(0);
	char *p, *rp;
	long len, rlen;

	if (iter || !NIL_P(hash)) {
	    p = RSTRING_PTR(str); len = RSTRING_LEN(str);

            if (iter) {
                repl = rb_obj_as_string(rb_yield(rb_reg_nth_match(0, match)));
            }
            else {
                repl = rb_hash_aref(hash, rb_str_subseq(str, beg0, end0 - beg0));
                repl = rb_obj_as_string(repl);
            }
	    str_mod_check(str, p, len);
	    rb_check_frozen(str);
	}
	else {
	    repl = rb_reg_regsub(repl, str, regs, pat);
	}
        enc = rb_enc_compatible(str, repl);
        if (!enc) {
            rb_encoding *str_enc = STR_ENC_GET(str);
	    p = RSTRING_PTR(str); len = RSTRING_LEN(str);
	    if (coderange_scan(p, beg0, str_enc) != ENC_CODERANGE_7BIT ||
		coderange_scan(p+end0, len-end0, str_enc) != ENC_CODERANGE_7BIT) {
                rb_raise(rb_eEncCompatError, "incompatible character encodings: %s and %s",
			 rb_enc_name(str_enc),
			 rb_enc_name(STR_ENC_GET(repl)));
            }
            enc = STR_ENC_GET(repl);
        }
	rb_str_modify(str);
	rb_enc_associate(str, enc);
	if (OBJ_TAINTED(repl)) tainted = 1;
	if (ENC_CODERANGE_UNKNOWN < cr && cr < ENC_CODERANGE_BROKEN) {
	    int cr2 = ENC_CODERANGE(repl);
            if (cr2 == ENC_CODERANGE_BROKEN ||
                (cr == ENC_CODERANGE_VALID && cr2 == ENC_CODERANGE_7BIT))
                cr = ENC_CODERANGE_UNKNOWN;
            else
                cr = cr2;
	}
	plen = end0 - beg0;
	rp = RSTRING_PTR(repl); rlen = RSTRING_LEN(repl);
	len = RSTRING_LEN(str);
	if (rlen > plen) {
	    RESIZE_CAPA(str, len + rlen - plen);
	}
	p = RSTRING_PTR(str);
	if (rlen != plen) {
	    memmove(p + beg0 + rlen, p + beg0 + plen, len - beg0 - plen);
	}
	memcpy(p + beg0, rp, rlen);
	len += rlen - plen;
	STR_SET_LEN(str, len);
	RSTRING_PTR(str)[len] = '\0';
	ENC_CODERANGE_SET(str, cr);
	if (tainted) OBJ_TAINT(str);

	return str;
    }
    return Qnil;
}

#succ ⇒ `String` #next ⇒ `String`

If the increment generates a “carry,” the character to the left of it is incremented. This process repeats until there is no carry, adding an additional character if necessary.

"abcd".succ        #=> "abce"
"THX1138".succ     #=> "THX1139"
"<<koala>>".succ   #=> "<<koalb>>"
"1999zzz".succ     #=> "2000aaa"
"ZZZ9999".succ     #=> "AAAA0000"
"***".succ         #=> "**+"

Overloads:

#succ ⇒ String
Returns:
- (String)
#next ⇒ String
Returns:
- (String)

# File 'string.c', line 3256

VALUE
rb_str_succ(VALUE orig)
{
    rb_encoding *enc;
    VALUE str;
    char *sbeg, *s, *e, *last_alnum = 0;
    int c = -1;
    long l;
    char carry[ONIGENC_CODE_TO_MBC_MAXLEN] = "\1";
    long carry_pos = 0, carry_len = 1;
    enum neighbor_char neighbor = NEIGHBOR_FOUND;

    str = rb_str_new5(orig, RSTRING_PTR(orig), RSTRING_LEN(orig));
    rb_enc_cr_str_copy_for_substr(str, orig);
    OBJ_INFECT(str, orig);
    if (RSTRING_LEN(str) == 0) return str;

    enc = STR_ENC_GET(orig);
    sbeg = RSTRING_PTR(str);
    s = e = sbeg + RSTRING_LEN(str);

    while ((s = rb_enc_prev_char(sbeg, s, e, enc)) != 0) {
	if (neighbor == NEIGHBOR_NOT_CHAR && last_alnum) {
	    if (ISALPHA(*last_alnum) ? ISDIGIT(*s) :
		ISDIGIT(*last_alnum) ? ISALPHA(*s) : 0) {
		s = last_alnum;
		break;
	    }
	}
	l = rb_enc_precise_mbclen(s, e, enc);
	if (!ONIGENC_MBCLEN_CHARFOUND_P(l)) continue;
	l = ONIGENC_MBCLEN_CHARFOUND_LEN(l);
        neighbor = enc_succ_alnum_char(s, l, enc, carry);
        switch (neighbor) {
	  case NEIGHBOR_NOT_CHAR:
	    continue;
	  case NEIGHBOR_FOUND:
	    return str;
	  case NEIGHBOR_WRAPPED:
	    last_alnum = s;
	    break;
	}
        c = 1;
        carry_pos = s - sbeg;
        carry_len = l;
    }
    if (c == -1) {		/* str contains no alnum */
	s = e;
	while ((s = rb_enc_prev_char(sbeg, s, e, enc)) != 0) {
            enum neighbor_char neighbor;
	    char tmp[ONIGENC_CODE_TO_MBC_MAXLEN];
	    l = rb_enc_precise_mbclen(s, e, enc);
	    if (!ONIGENC_MBCLEN_CHARFOUND_P(l)) continue;
	    l = ONIGENC_MBCLEN_CHARFOUND_LEN(l);
	    MEMCPY(tmp, s, char, l);
	    neighbor = enc_succ_char(tmp, l, enc);
	    switch (neighbor) {
	      case NEIGHBOR_FOUND:
		MEMCPY(s, tmp, char, l);
                return str;
		break;
	      case NEIGHBOR_WRAPPED:
		MEMCPY(s, tmp, char, l);
		break;
	      case NEIGHBOR_NOT_CHAR:
		break;
	    }
            if (rb_enc_precise_mbclen(s, s+l, enc) != l) {
                /* wrapped to \0...\0.  search next valid char. */
                enc_succ_char(s, l, enc);
            }
            if (!rb_enc_asciicompat(enc)) {
                MEMCPY(carry, s, char, l);
                carry_len = l;
            }
            carry_pos = s - sbeg;
	}
    }
    RESIZE_CAPA(str, RSTRING_LEN(str) + carry_len);
    s = RSTRING_PTR(str) + carry_pos;
    memmove(s + carry_len, s, RSTRING_LEN(str) - carry_pos);
    memmove(s, carry, carry_len);
    STR_SET_LEN(str, RSTRING_LEN(str) + carry_len);
    RSTRING_PTR(str)[RSTRING_LEN(str)] = '\0';
    rb_enc_str_coderange(str);
    return str;
}

#succ! ⇒ `String` #next! ⇒ `String`

Equivalent to String#succ, but modifies the receiver in place.

Overloads:

#succ! ⇒ String
Returns:
- (String)
#next! ⇒ String
Returns:
- (String)

# File 'string.c', line 3354

static VALUE
rb_str_succ_bang(VALUE str)
{
    rb_str_shared_replace(str, rb_str_succ(str));

    return str;
}

#sum(n = 16) ⇒ `Integer`

Returns a basic n-bit checksum of the characters in str, where n is the optional Fixnum parameter, defaulting to 16. The result is simply the sum of the binary value of each character in str modulo 2**n - 1. This is not a particularly good checksum.

Returns:

(Integer)

# File 'string.c', line 7508

static VALUE
rb_str_sum(int argc, VALUE *argv, VALUE str)
{
    VALUE vbits;
    int bits;
    char *ptr, *p, *pend;
    long len;
    VALUE sum = INT2FIX(0);
    unsigned long sum0 = 0;

    if (argc == 0) {
	bits = 16;
    }
    else {
	rb_scan_args(argc, argv, "01", &vbits);
	bits = NUM2INT(vbits);
    }
    ptr = p = RSTRING_PTR(str);
    len = RSTRING_LEN(str);
    pend = p + len;

    while (p < pend) {
        if (FIXNUM_MAX - UCHAR_MAX < sum0) {
            sum = rb_funcall(sum, '+', 1, LONG2FIX(sum0));
            str_mod_check(str, ptr, len);
            sum0 = 0;
        }
        sum0 += (unsigned char)*p;
        p++;
    }

    if (bits == 0) {
        if (sum0) {
            sum = rb_funcall(sum, '+', 1, LONG2FIX(sum0));
        }
    }
    else {
        if (sum == INT2FIX(0)) {
            if (bits < (int)sizeof(long)*CHAR_BIT) {
                sum0 &= (((unsigned long)1)<<bits)-1;
            }
            sum = LONG2FIX(sum0);
        }
        else {
            VALUE mod;

            if (sum0) {
                sum = rb_funcall(sum, '+', 1, LONG2FIX(sum0));
            }

            mod = rb_funcall(INT2FIX(1), rb_intern("<<"), 1, INT2FIX(bits));
            mod = rb_funcall(mod, '-', 1, INT2FIX(1));
            sum = rb_funcall(sum, '&', 1, mod);
        }
    }
    return sum;
}

#swapcase ⇒ `String`

Returns a copy of str with uppercase alphabetic characters converted to lowercase and lowercase characters converted to uppercase. Note: case conversion is effective only in ASCII region.

"Hello".swapcase          #=> "hELLO"
"cYbEr_PuNk11".swapcase   #=> "CyBeR_pUnK11"

Returns:

(String)

# File 'string.c', line 5330

static VALUE
rb_str_swapcase(VALUE str)
{
    str = rb_str_dup(str);
    rb_str_swapcase_bang(str);
    return str;
}

#swapcase! ⇒ `String`^?

Equivalent to String#swapcase, but modifies the receiver in place, returning str, or nil if no changes were made. Note: case conversion is effective only in ASCII region.

Returns:

(String, nil)

# File 'string.c', line 5285

static VALUE
rb_str_swapcase_bang(VALUE str)
{
    rb_encoding *enc;
    char *s, *send;
    int modify = 0;
    int n;

    str_modify_keep_cr(str);
    enc = STR_ENC_GET(str);
    rb_str_check_dummy_enc(enc);
    s = RSTRING_PTR(str); send = RSTRING_END(str);
    while (s < send) {
	unsigned int c = rb_enc_codepoint_len(s, send, &n, enc);

	if (rb_enc_isupper(c, enc)) {
	    /* assuming toupper returns codepoint with same size */
	    rb_enc_mbcput(rb_enc_tolower(c, enc), s, enc);
	    modify = 1;
	}
	else if (rb_enc_islower(c, enc)) {
	    /* assuming tolower returns codepoint with same size */
	    rb_enc_mbcput(rb_enc_toupper(c, enc), s, enc);
	    modify = 1;
	}
	s += n;
    }

    if (modify) return str;
    return Qnil;
}

#to_c ⇒ `Object`

Returns a complex which denotes the string form. The parser ignores leading whitespaces and trailing garbage. Any digit sequences can be separated by an underscore. Returns zero for null or garbage string.

'9'.to_c           #=> (9+0i)
'2.5'.to_c         #=> (2.5+0i)
'2.5/1'.to_c       #=> ((5/2)+0i)
'-3/2'.to_c        #=> ((-3/2)+0i)
'-i'.to_c          #=> (0-1i)
'45i'.to_c         #=> (0+45i)
'3-4i'.to_c        #=> (3-4i)
'-4e2-4e-2i'.to_c  #=> (-400.0-0.04i)
'-0.0-0.0i'.to_c   #=> (-0.0-0.0i)
'1/2+3/4i'.to_c    #=> ((1/2)+(3/4)*i)
'ruby'.to_c        #=> (0+0i)

See Kernel.Complex.

# File 'complex.c', line 1811

static VALUE
string_to_c(VALUE self)
{
    char *s;
    VALUE num;

    rb_must_asciicompat(self);

    s = RSTRING_PTR(self);

    if (s && s[RSTRING_LEN(self)]) {
	rb_str_modify(self);
	s = RSTRING_PTR(self);
	s[RSTRING_LEN(self)] = '\0';
    }

    if (!s)
	s = (char *)"";

    (void)parse_comp(s, 0, &num);

    return num;
}

#to_f ⇒ `Float`

Returns the result of interpreting leading characters in str as a floating point number. Extraneous characters past the end of a valid number are ignored. If there is not a valid number at the start of str, 0.0 is returned. This method never raises an exception.

"123.45e1".to_f        #=> 1234.5
"45.67 degrees".to_f   #=> 45.67
"thx1138".to_f         #=> 0.0

Returns:

(Float)

# File 'string.c', line 4708

static VALUE
rb_str_to_f(VALUE str)
{
    return DBL2NUM(rb_str_to_dbl(str, FALSE));
}

#to_i(base = 10) ⇒ `Integer`

Returns the result of interpreting leading characters in str as an integer base base (between 2 and 36). Extraneous characters past the end of a valid number are ignored. If there is not a valid number at the start of str, 0 is returned. This method never raises an exception when base is valid.

"12345".to_i             #=> 12345
"99 red balloons".to_i   #=> 99
"0a".to_i                #=> 0
"0a".to_i(16)            #=> 10
"hello".to_i             #=> 0
"1100101".to_i(2)        #=> 101
"1100101".to_i(8)        #=> 294977
"1100101".to_i(10)       #=> 1100101
"1100101".to_i(16)       #=> 17826049

Returns:

(Integer)

# File 'string.c', line 4675

static VALUE
rb_str_to_i(int argc, VALUE *argv, VALUE str)
{
    int base;

    if (argc == 0) base = 10;
    else {
	VALUE b;

	rb_scan_args(argc, argv, "01", &b);
	base = NUM2INT(b);
    }
    if (base < 0) {
	rb_raise(rb_eArgError, "invalid radix %d", base);
    }
    return rb_str_to_inum(str, base, FALSE);
}

#to_r ⇒ `Object`

Returns a rational which denotes the string form. The parser ignores leading whitespaces and trailing garbage. Any digit sequences can be separated by an underscore. Returns zero for null or garbage string.

NOTE: ‘0.3’.to_r isn’t the same as 0.3.to_r. The former is equivalent to ‘3/10’.to_r, but the latter isn’t so.

'  2  '.to_r       #=> (2/1)
'300/2'.to_r       #=> (150/1)
'-9.2'.to_r        #=> (-46/5)
'-9.2e2'.to_r      #=> (-920/1)
'1_234_567'.to_r   #=> (1234567/1)
'21 june 09'.to_r  #=> (21/1)
'21/06/09'.to_r    #=> (7/2)
'bwv 1079'.to_r    #=> (0/1)

See Kernel.Rational.

# File 'rational.c', line 2349

static VALUE
string_to_r(VALUE self)
{
    char *s;
    VALUE num;

    rb_must_asciicompat(self);

    s = RSTRING_PTR(self);

    if (s && s[RSTRING_LEN(self)]) {
	rb_str_modify(self);
	s = RSTRING_PTR(self);
	s[RSTRING_LEN(self)] = '\0';
    }

    if (!s)
	s = (char *)"";

    (void)parse_rat(s, 0, &num);

    if (RB_TYPE_P(num, T_FLOAT))
	rb_raise(rb_eFloatDomainError, "Infinity");
    return num;
}

#to_s ⇒ `String` #to_str ⇒ `String`

Returns the receiver.

Overloads:

#to_s ⇒ String
Returns:
- (String)
#to_str ⇒ String
Returns:
- (String)

# File 'string.c', line 4723

static VALUE
rb_str_to_s(VALUE str)
{
    if (rb_obj_class(str) != rb_cString) {
	return str_duplicate(rb_cString, str);
    }
    return str;
}

#to_s ⇒ `String` #to_str ⇒ `String`

Returns the receiver.

Overloads:

#to_s ⇒ String
Returns:
- (String)
#to_str ⇒ String
Returns:
- (String)

# File 'string.c', line 4723

static VALUE
rb_str_to_s(VALUE str)
{
    if (rb_obj_class(str) != rb_cString) {
	return str_duplicate(rb_cString, str);
    }
    return str;
}

#intern ⇒ `Object` #to_sym ⇒ `Object`

Returns the Symbol corresponding to str, creating the symbol if it did not previously exist. See Symbol#id2name.

"Koala".intern         #=> :Koala
s = 'cat'.to_sym       #=> :cat
s == :cat              #=> true
s = '@cat'.to_sym      #=> :@cat
s == :@cat             #=> true

This can also be used to create symbols that cannot be represented using the :xxx notation.

'cat and dog'.to_sym   #=> :"cat and dog"

# File 'string.c', line 7469

VALUE
rb_str_intern(VALUE s)
{
    VALUE str = RB_GC_GUARD(s);
    ID id;

    id = rb_intern_str(str);
    return ID2SYM(id);
}

#tr(from_str, to_str) ⇒ `String`

Returns a copy of str with the characters in from_str replaced by the corresponding characters in to_str. If to_str is shorter than from_str, it is padded with its last character in order to maintain the correspondence.

"hello".tr('el', 'ip')      #=> "hippo"
"hello".tr('aeiou', '*')    #=> "h*ll*"
"hello".tr('aeiou', 'AA*')  #=> "hAll*"

Both strings may use the c1-c2 notation to denote ranges of characters, and from_str may start with a ^, which denotes all characters except those listed.

"hello".tr('a-y', 'b-z')    #=> "ifmmp"
"hello".tr('^aeiou', '*')   #=> "*e**o"

The backslash character </code> can be used to escape <code>^ or - and is otherwise ignored unless it appears at the end of a range or the end of the from_str or to_str:

"hello^world".tr("\\^aeiou", "*") #=> "h*ll**w*rld"
"hello-world".tr("a\\-eo", "*")   #=> "h*ll**w*rld"

"hello\r\nworld".tr("\r", "")   #=> "hello\nworld"
"hello\r\nworld".tr("\\r", "")  #=> "hello\r\nwold"
"hello\r\nworld".tr("\\\r", "") #=> "hello\nworld"

"X['\\b']".tr("X\\", "")   #=> "['b']"
"X['\\b']".tr("X-\\]", "") #=> "'b'"

Returns:

(String)

# File 'string.c', line 5698

static VALUE
rb_str_tr(VALUE str, VALUE src, VALUE repl)
{
    str = rb_str_dup(str);
    tr_trans(str, src, repl, 0);
    return str;
}

#tr!(from_str, to_str) ⇒ `String`^?

Translates str in place, using the same rules as String#tr. Returns str, or nil if no changes were made.

Returns:

(String, nil)

# File 'string.c', line 5656

static VALUE
rb_str_tr_bang(VALUE str, VALUE src, VALUE repl)
{
    return tr_trans(str, src, repl, 0);
}

#tr_s(from_str, to_str) ⇒ `String`

Processes a copy of str as described under String#tr, then removes duplicate characters in regions that were affected by the translation.

"hello".tr_s('l', 'r')     #=> "hero"
"hello".tr_s('el', '*')    #=> "h*o"
"hello".tr_s('el', 'hx')   #=> "hhxo"

Returns:

(String)

# File 'string.c', line 6021

static VALUE
rb_str_tr_s(VALUE str, VALUE src, VALUE repl)
{
    str = rb_str_dup(str);
    tr_trans(str, src, repl, 1);
    return str;
}

#tr_s!(from_str, to_str) ⇒ `String`^?

Performs String#tr_s processing on str in place, returning str, or nil if no changes were made.

Returns:

(String, nil)

# File 'string.c', line 6001

static VALUE
rb_str_tr_s_bang(VALUE str, VALUE src, VALUE repl)
{
    return tr_trans(str, src, repl, 1);
}

#unpack(format) ⇒ `Array`

Decodes str (which may contain binary data) according to the format string, returning an array of each value extracted. The format string consists of a sequence of single-character directives, summarized in the table at the end of this entry. Each directive may be followed by a number, indicating the number of times to repeat with this directive. An asterisk (“*”) will use up all remaining elements. The directives sSiIlL may each be followed by an underscore (“_”) or exclamation mark (“!”) to use the underlying platform’s native size for the specified type; otherwise, it uses a platform-independent consistent size. Spaces are ignored in the format string. See also Array#pack.

"abc \0\0abc \0\0".unpack('A6Z6')   #=> ["abc", "abc "]
"abc \0\0".unpack('a3a3')           #=> ["abc", " \000\000"]
"abc \0abc \0".unpack('Z*Z*')       #=> ["abc ", "abc "]
"aa".unpack('b8B8')                 #=> ["10000110", "01100001"]
"aaa".unpack('h2H2c')               #=> ["16", "61", 97]
"\xfe\xff\xfe\xff".unpack('sS')     #=> [-2, 65534]
"now=20is".unpack('M*')             #=> ["now is"]
"whole".unpack('xax2aX2aX1aX2a')    #=> ["h", "e", "l", "l", "o"]

This table summarizes the various formats and the Ruby classes returned by each.

Integer      |         |
Directive    | Returns | Meaning
-----------------------------------------------------------------
   C         | Integer | 8-bit unsigned (unsigned char)
   S         | Integer | 16-bit unsigned, native endian (uint16_t)
   L         | Integer | 32-bit unsigned, native endian (uint32_t)
   Q         | Integer | 64-bit unsigned, native endian (uint64_t)
             |         |
   c         | Integer | 8-bit signed (signed char)
   s         | Integer | 16-bit signed, native endian (int16_t)
   l         | Integer | 32-bit signed, native endian (int32_t)
   q         | Integer | 64-bit signed, native endian (int64_t)
             |         |
   S_, S!    | Integer | unsigned short, native endian
   I, I_, I! | Integer | unsigned int, native endian
   L_, L!    | Integer | unsigned long, native endian
   Q_, Q!    | Integer | unsigned long long, native endian (ArgumentError
             |         | if the platform has no long long type.)
             |         | (Q_ and Q! is available since Ruby 2.1.)
             |         |
   s_, s!    | Integer | signed short, native endian
   i, i_, i! | Integer | signed int, native endian
   l_, l!    | Integer | signed long, native endian
   q_, q!    | Integer | signed long long, native endian (ArgumentError
             |         | if the platform has no long long type.)
             |         | (q_ and q! is available since Ruby 2.1.)
             |         |
   S> L> Q>  | Integer | same as the directives without ">" except
   s> l> q>  |         | big endian
   S!> I!>   |         | (available since Ruby 1.9.3)
   L!> Q!>   |         | "S>" is same as "n"
   s!> i!>   |         | "L>" is same as "N"
   l!> q!>   |         |
             |         |
   S< L< Q<  | Integer | same as the directives without "<" except
   s< l< q<  |         | little endian
   S!< I!<   |         | (available since Ruby 1.9.3)
   L!< Q!<   |         | "S<" is same as "v"
   s!< i!<   |         | "L<" is same as "V"
   l!< q!<   |         |
             |         |
   n         | Integer | 16-bit unsigned, network (big-endian) byte order
   N         | Integer | 32-bit unsigned, network (big-endian) byte order
   v         | Integer | 16-bit unsigned, VAX (little-endian) byte order
   V         | Integer | 32-bit unsigned, VAX (little-endian) byte order
             |         |
   U         | Integer | UTF-8 character
   w         | Integer | BER-compressed integer (see Array.pack)

Float        |         |
Directive    | Returns | Meaning
-----------------------------------------------------------------
   D, d      | Float   | double-precision, native format
   F, f      | Float   | single-precision, native format
   E         | Float   | double-precision, little-endian byte order
   e         | Float   | single-precision, little-endian byte order
   G         | Float   | double-precision, network (big-endian) byte order
   g         | Float   | single-precision, network (big-endian) byte order

String       |         |
Directive    | Returns | Meaning
-----------------------------------------------------------------
   A         | String  | arbitrary binary string (remove trailing nulls and ASCII spaces)
   a         | String  | arbitrary binary string
   Z         | String  | null-terminated string
   B         | String  | bit string (MSB first)
   b         | String  | bit string (LSB first)
   H         | String  | hex string (high nibble first)
   h         | String  | hex string (low nibble first)
   u         | String  | UU-encoded string
   M         | String  | quoted-printable, MIME encoding (see RFC2045)
   m         | String  | base64 encoded string (RFC 2045) (default)
             |         | base64 encoded string (RFC 4648) if followed by 0
   P         | String  | pointer to a structure (fixed-length string)
   p         | String  | pointer to a null-terminated string

Misc.        |         |
Directive    | Returns | Meaning
-----------------------------------------------------------------
   @         | ---     | skip to the offset given by the length argument
   X         | ---     | skip backward one byte
   x         | ---     | skip forward one byte

Returns:

(Array)

# File 'pack.c', line 1197

static VALUE
pack_unpack(VALUE str, VALUE fmt)
{
    static const char hexdigits[] = "0123456789abcdef";
    char *s, *send;
    char *p, *pend;
    VALUE ary;
    char type;
    long len, tmp_len;
    int star;
#ifdef NATINT_PACK
    int natint;			/* native integer */
#endif
    int block_p = rb_block_given_p();
    int signed_p, integer_size, bigendian_p;
#define UNPACK_PUSH(item) do {\
	VALUE item_val = (item);\
	if (block_p) {\
	    rb_yield(item_val);\
	}\
	else {\
	    rb_ary_push(ary, item_val);\
	}\
    } while (0)

    StringValue(str);
    StringValue(fmt);
    s = RSTRING_PTR(str);
    send = s + RSTRING_LEN(str);
    p = RSTRING_PTR(fmt);
    pend = p + RSTRING_LEN(fmt);

    ary = block_p ? Qnil : rb_ary_new();
    while (p < pend) {
	int explicit_endian = 0;
	type = *p++;
#ifdef NATINT_PACK
	natint = 0;
#endif

	if (ISSPACE(type)) continue;
	if (type == '#') {
	    while ((p < pend) && (*p != '\n')) {
		p++;
	    }
	    continue;
	}

	star = 0;
	{
          modifiers:
	    switch (*p) {
	      case '_':
	      case '!':

		if (strchr(natstr, type)) {
#ifdef NATINT_PACK
		    natint = 1;
#endif
		    p++;
		}
		else {
		    rb_raise(rb_eArgError, "'%c' allowed only after types %s", *p, natstr);
		}
		goto modifiers;

	      case '<':
	      case '>':
		if (!strchr(endstr, type)) {
		    rb_raise(rb_eArgError, "'%c' allowed only after types %s", *p, endstr);
		}
		if (explicit_endian) {
		    rb_raise(rb_eRangeError, "Can't use both '<' and '>'");
		}
		explicit_endian = *p++;
		goto modifiers;
	    }
	}

	if (p >= pend)
	    len = 1;
	else if (*p == '*') {
	    star = 1;
	    len = send - s;
	    p++;
	}
	else if (ISDIGIT(*p)) {
	    errno = 0;
	    len = STRTOUL(p, (char**)&p, 10);
	    if (errno) {
		rb_raise(rb_eRangeError, "pack length too big");
	    }
	}
	else {
	    len = (type != '@');
	}

	switch (type) {
	  case '%':
	    rb_raise(rb_eArgError, "%% is not supported");
	    break;

	  case 'A':
	    if (len > send - s) len = send - s;
	    {
		long end = len;
		char *t = s + len - 1;

		while (t >= s) {
		    if (*t != ' ' && *t != '\0') break;
		    t--; len--;
		}
		UNPACK_PUSH(infected_str_new(s, len, str));
		s += end;
	    }
	    break;

	  case 'Z':
	    {
		char *t = s;

		if (len > send-s) len = send-s;
		while (t < s+len && *t) t++;
		UNPACK_PUSH(infected_str_new(s, t-s, str));
		if (t < send) t++;
		s = star ? t : s+len;
	    }
	    break;

	  case 'a':
	    if (len > send - s) len = send - s;
	    UNPACK_PUSH(infected_str_new(s, len, str));
	    s += len;
	    break;

	  case 'b':
	    {
		VALUE bitstr;
		char *t;
		int bits;
		long i;

		if (p[-1] == '*' || len > (send - s) * 8)
		    len = (send - s) * 8;
		bits = 0;
		UNPACK_PUSH(bitstr = rb_usascii_str_new(0, len));
		t = RSTRING_PTR(bitstr);
		for (i=0; i<len; i++) {
		    if (i & 7) bits >>= 1;
		    else bits = *s++;
		    *t++ = (bits & 1) ? '1' : '0';
		}
	    }
	    break;

	  case 'B':
	    {
		VALUE bitstr;
		char *t;
		int bits;
		long i;

		if (p[-1] == '*' || len > (send - s) * 8)
		    len = (send - s) * 8;
		bits = 0;
		UNPACK_PUSH(bitstr = rb_usascii_str_new(0, len));
		t = RSTRING_PTR(bitstr);
		for (i=0; i<len; i++) {
		    if (i & 7) bits <<= 1;
		    else bits = *s++;
		    *t++ = (bits & 128) ? '1' : '0';
		}
	    }
	    break;

	  case 'h':
	    {
		VALUE bitstr;
		char *t;
		int bits;
		long i;

		if (p[-1] == '*' || len > (send - s) * 2)
		    len = (send - s) * 2;
		bits = 0;
		UNPACK_PUSH(bitstr = rb_usascii_str_new(0, len));
		t = RSTRING_PTR(bitstr);
		for (i=0; i<len; i++) {
		    if (i & 1)
			bits >>= 4;
		    else
			bits = *s++;
		    *t++ = hexdigits[bits & 15];
		}
	    }
	    break;

	  case 'H':
	    {
		VALUE bitstr;
		char *t;
		int bits;
		long i;

		if (p[-1] == '*' || len > (send - s) * 2)
		    len = (send - s) * 2;
		bits = 0;
		UNPACK_PUSH(bitstr = rb_usascii_str_new(0, len));
		t = RSTRING_PTR(bitstr);
		for (i=0; i<len; i++) {
		    if (i & 1)
			bits <<= 4;
		    else
			bits = *s++;
		    *t++ = hexdigits[(bits >> 4) & 15];
		}
	    }
	    break;

	  case 'c':
	    signed_p = 1;
	    integer_size = 1;
	    bigendian_p = BIGENDIAN_P(); /* not effective */
	    goto unpack_integer;

	  case 'C':
	    signed_p = 0;
	    integer_size = 1;
	    bigendian_p = BIGENDIAN_P(); /* not effective */
	    goto unpack_integer;

	  case 's':
	    signed_p = 1;
	    integer_size = NATINT_LEN(short, 2);
	    bigendian_p = BIGENDIAN_P();
	    goto unpack_integer;

	  case 'S':
	    signed_p = 0;
	    integer_size = NATINT_LEN(short, 2);
	    bigendian_p = BIGENDIAN_P();
	    goto unpack_integer;

	  case 'i':
	    signed_p = 1;
	    integer_size = (int)sizeof(int);
	    bigendian_p = BIGENDIAN_P();
	    goto unpack_integer;

	  case 'I':
	    signed_p = 0;
	    integer_size = (int)sizeof(int);
	    bigendian_p = BIGENDIAN_P();
	    goto unpack_integer;

	  case 'l':
	    signed_p = 1;
	    integer_size = NATINT_LEN(long, 4);
	    bigendian_p = BIGENDIAN_P();
	    goto unpack_integer;

	  case 'L':
	    signed_p = 0;
	    integer_size = NATINT_LEN(long, 4);
	    bigendian_p = BIGENDIAN_P();
	    goto unpack_integer;

	  case 'q':
	    signed_p = 1;
	    integer_size = NATINT_LEN_Q;
	    bigendian_p = BIGENDIAN_P();
	    goto unpack_integer;

	  case 'Q':
	    signed_p = 0;
	    integer_size = NATINT_LEN_Q;
	    bigendian_p = BIGENDIAN_P();
	    goto unpack_integer;

	  case 'n':
	    signed_p = 0;
	    integer_size = 2;
	    bigendian_p = 1;
	    goto unpack_integer;

	  case 'N':
	    signed_p = 0;
	    integer_size = 4;
	    bigendian_p = 1;
	    goto unpack_integer;

	  case 'v':
	    signed_p = 0;
	    integer_size = 2;
	    bigendian_p = 0;
	    goto unpack_integer;

	  case 'V':
	    signed_p = 0;
	    integer_size = 4;
	    bigendian_p = 0;
	    goto unpack_integer;

	  unpack_integer:
	    if (explicit_endian) {
		bigendian_p = explicit_endian == '>';
	    }
            PACK_LENGTH_ADJUST_SIZE(integer_size);
            while (len-- > 0) {
                int flags = bigendian_p ? INTEGER_PACK_BIG_ENDIAN : INTEGER_PACK_LITTLE_ENDIAN;
                VALUE val;
                if (signed_p)
                    flags |= INTEGER_PACK_2COMP;
                val = rb_integer_unpack(s, integer_size, 1, 0, flags);
                UNPACK_PUSH(val);
                s += integer_size;
            }
            PACK_ITEM_ADJUST();
            break;

	  case 'f':
	  case 'F':
	    PACK_LENGTH_ADJUST_SIZE(sizeof(float));
	    while (len-- > 0) {
		float tmp;
		memcpy(&tmp, s, sizeof(float));
		s += sizeof(float);
		UNPACK_PUSH(DBL2NUM((double)tmp));
	    }
	    PACK_ITEM_ADJUST();
	    break;

	  case 'e':
	    PACK_LENGTH_ADJUST_SIZE(sizeof(float));
	    while (len-- > 0) {
	        float tmp;
		FLOAT_CONVWITH(ftmp);

		memcpy(&tmp, s, sizeof(float));
		s += sizeof(float);
		tmp = VTOHF(tmp,ftmp);
		UNPACK_PUSH(DBL2NUM((double)tmp));
	    }
	    PACK_ITEM_ADJUST();
	    break;

	  case 'E':
	    PACK_LENGTH_ADJUST_SIZE(sizeof(double));
	    while (len-- > 0) {
		double tmp;
		DOUBLE_CONVWITH(dtmp);

		memcpy(&tmp, s, sizeof(double));
		s += sizeof(double);
		tmp = VTOHD(tmp,dtmp);
		UNPACK_PUSH(DBL2NUM(tmp));
	    }
	    PACK_ITEM_ADJUST();
	    break;

	  case 'D':
	  case 'd':
	    PACK_LENGTH_ADJUST_SIZE(sizeof(double));
	    while (len-- > 0) {
		double tmp;
		memcpy(&tmp, s, sizeof(double));
		s += sizeof(double);
		UNPACK_PUSH(DBL2NUM(tmp));
	    }
	    PACK_ITEM_ADJUST();
	    break;

	  case 'g':
	    PACK_LENGTH_ADJUST_SIZE(sizeof(float));
	    while (len-- > 0) {
	        float tmp;
		FLOAT_CONVWITH(ftmp);

		memcpy(&tmp, s, sizeof(float));
		s += sizeof(float);
		tmp = NTOHF(tmp,ftmp);
		UNPACK_PUSH(DBL2NUM((double)tmp));
	    }
	    PACK_ITEM_ADJUST();
	    break;

	  case 'G':
	    PACK_LENGTH_ADJUST_SIZE(sizeof(double));
	    while (len-- > 0) {
		double tmp;
		DOUBLE_CONVWITH(dtmp);

		memcpy(&tmp, s, sizeof(double));
		s += sizeof(double);
		tmp = NTOHD(tmp,dtmp);
		UNPACK_PUSH(DBL2NUM(tmp));
	    }
	    PACK_ITEM_ADJUST();
	    break;

	  case 'U':
	    if (len > send - s) len = send - s;
	    while (len > 0 && s < send) {
		long alen = send - s;
		unsigned long l;

		l = utf8_to_uv(s, &alen);
		s += alen; len--;
		UNPACK_PUSH(ULONG2NUM(l));
	    }
	    break;

	  case 'u':
	    {
		VALUE buf = infected_str_new(0, (send - s)*3/4, str);
		char *ptr = RSTRING_PTR(buf);
		long total = 0;

		while (s < send && *s > ' ' && *s < 'a') {
		    long a,b,c,d;
		    char hunk[4];

		    hunk[3] = '\0';
		    len = (*s++ - ' ') & 077;
		    total += len;
		    if (total > RSTRING_LEN(buf)) {
			len -= total - RSTRING_LEN(buf);
			total = RSTRING_LEN(buf);
		    }

		    while (len > 0) {
			long mlen = len > 3 ? 3 : len;

			if (s < send && *s >= ' ')
			    a = (*s++ - ' ') & 077;
			else
			    a = 0;
			if (s < send && *s >= ' ')
			    b = (*s++ - ' ') & 077;
			else
			    b = 0;
			if (s < send && *s >= ' ')
			    c = (*s++ - ' ') & 077;
			else
			    c = 0;
			if (s < send && *s >= ' ')
			    d = (*s++ - ' ') & 077;
			else
			    d = 0;
			hunk[0] = (char)(a << 2 | b >> 4);
			hunk[1] = (char)(b << 4 | c >> 2);
			hunk[2] = (char)(c << 6 | d);
			memcpy(ptr, hunk, mlen);
			ptr += mlen;
			len -= mlen;
		    }
		    if (*s == '\r') s++;
		    if (*s == '\n') s++;
		    else if (s < send && (s+1 == send || s[1] == '\n'))
			s += 2;	/* possible checksum byte */
		}

		rb_str_set_len(buf, total);
		UNPACK_PUSH(buf);
	    }
	    break;

	  case 'm':
	    {
		VALUE buf = infected_str_new(0, (send - s + 3)*3/4, str); /* +3 is for skipping paddings */
		char *ptr = RSTRING_PTR(buf);
		int a = -1,b = -1,c = 0,d = 0;
		static signed char b64_xtable[256];

		if (b64_xtable['/'] <= 0) {
		    int i;

		    for (i = 0; i < 256; i++) {
			b64_xtable[i] = -1;
		    }
		    for (i = 0; i < 64; i++) {
			b64_xtable[(unsigned char)b64_table[i]] = (char)i;
		    }
		}
		if (len == 0) {
		    while (s < send) {
			a = b = c = d = -1;
			a = b64_xtable[(unsigned char)*s++];
			if (s >= send || a == -1) rb_raise(rb_eArgError, "invalid base64");
			b = b64_xtable[(unsigned char)*s++];
			if (s >= send || b == -1) rb_raise(rb_eArgError, "invalid base64");
			if (*s == '=') {
			    if (s + 2 == send && *(s + 1) == '=') break;
			    rb_raise(rb_eArgError, "invalid base64");
			}
			c = b64_xtable[(unsigned char)*s++];
			if (s >= send || c == -1) rb_raise(rb_eArgError, "invalid base64");
			if (s + 1 == send && *s == '=') break;
			d = b64_xtable[(unsigned char)*s++];
			if (d == -1) rb_raise(rb_eArgError, "invalid base64");
			*ptr++ = castchar(a << 2 | b >> 4);
			*ptr++ = castchar(b << 4 | c >> 2);
			*ptr++ = castchar(c << 6 | d);
		    }
		    if (c == -1) {
			*ptr++ = castchar(a << 2 | b >> 4);
			if (b & 0xf) rb_raise(rb_eArgError, "invalid base64");
		    }
		    else if (d == -1) {
			*ptr++ = castchar(a << 2 | b >> 4);
			*ptr++ = castchar(b << 4 | c >> 2);
			if (c & 0x3) rb_raise(rb_eArgError, "invalid base64");
		    }
		}
		else {
		    while (s < send) {
			a = b = c = d = -1;
			while ((a = b64_xtable[(unsigned char)*s]) == -1 && s < send) {s++;}
			if (s >= send) break;
			s++;
			while ((b = b64_xtable[(unsigned char)*s]) == -1 && s < send) {s++;}
			if (s >= send) break;
			s++;
			while ((c = b64_xtable[(unsigned char)*s]) == -1 && s < send) {if (*s == '=') break; s++;}
			if (*s == '=' || s >= send) break;
			s++;
			while ((d = b64_xtable[(unsigned char)*s]) == -1 && s < send) {if (*s == '=') break; s++;}
			if (*s == '=' || s >= send) break;
			s++;
			*ptr++ = castchar(a << 2 | b >> 4);
			*ptr++ = castchar(b << 4 | c >> 2);
			*ptr++ = castchar(c << 6 | d);
			a = -1;
		    }
		    if (a != -1 && b != -1) {
			if (c == -1)
			    *ptr++ = castchar(a << 2 | b >> 4);
			else {
			    *ptr++ = castchar(a << 2 | b >> 4);
			    *ptr++ = castchar(b << 4 | c >> 2);
			}
		    }
		}
		rb_str_set_len(buf, ptr - RSTRING_PTR(buf));
		UNPACK_PUSH(buf);
	    }
	    break;

	  case 'M':
	    {
		VALUE buf = infected_str_new(0, send - s, str);
		char *ptr = RSTRING_PTR(buf), *ss = s;
		int c1, c2;

		while (s < send) {
		    if (*s == '=') {
			if (++s == send) break;
			if (s+1 < send && *s == '\r' && *(s+1) == '\n')
			    s++;
			if (*s != '\n') {
			    if ((c1 = hex2num(*s)) == -1) break;
			    if (++s == send) break;
			    if ((c2 = hex2num(*s)) == -1) break;
			    *ptr++ = castchar(c1 << 4 | c2);
			}
		    }
		    else {
			*ptr++ = *s;
		    }
		    s++;
		    ss = s;
		}
		rb_str_set_len(buf, ptr - RSTRING_PTR(buf));
		rb_str_buf_cat(buf, ss, send-ss);
		ENCODING_CODERANGE_SET(buf, rb_ascii8bit_encindex(), ENC_CODERANGE_VALID);
		UNPACK_PUSH(buf);
	    }
	    break;

	  case '@':
	    if (len > RSTRING_LEN(str))
		rb_raise(rb_eArgError, "@ outside of string");
	    s = RSTRING_PTR(str) + len;
	    break;

	  case 'X':
	    if (len > s - RSTRING_PTR(str))
		rb_raise(rb_eArgError, "X outside of string");
	    s -= len;
	    break;

	  case 'x':
	    if (len > send - s)
		rb_raise(rb_eArgError, "x outside of string");
	    s += len;
	    break;

	  case 'P':
	    if (sizeof(char *) <= (size_t)(send - s)) {
		VALUE tmp = Qnil;
		char *t;

		memcpy(&t, s, sizeof(char *));
		s += sizeof(char *);

		if (t) {
		    VALUE a;
		    const VALUE *p, *pend;

		    if (!(a = rb_str_associated(str))) {
			rb_raise(rb_eArgError, "no associated pointer");
		    }
		    p = RARRAY_CONST_PTR(a);
		    pend = p + RARRAY_LEN(a);
		    while (p < pend) {
			if (RB_TYPE_P(*p, T_STRING) && RSTRING_PTR(*p) == t) {
			    if (len < RSTRING_LEN(*p)) {
				tmp = rb_tainted_str_new(t, len);
				rb_str_associate(tmp, a);
			    }
			    else {
				tmp = *p;
			    }
			    break;
			}
			p++;
		    }
		    if (p == pend) {
			rb_raise(rb_eArgError, "non associated pointer");
		    }
		}
		UNPACK_PUSH(tmp);
	    }
	    break;

	  case 'p':
	    if (len > (long)((send - s) / sizeof(char *)))
		len = (send - s) / sizeof(char *);
	    while (len-- > 0) {
		if ((size_t)(send - s) < sizeof(char *))
		    break;
		else {
		    VALUE tmp = Qnil;
		    char *t;

		    memcpy(&t, s, sizeof(char *));
		    s += sizeof(char *);

		    if (t) {
			VALUE a;
			const VALUE *p, *pend;

			if (!(a = rb_str_associated(str))) {
			    rb_raise(rb_eArgError, "no associated pointer");
			}
			p = RARRAY_CONST_PTR(a);
			pend = p + RARRAY_LEN(a);
			while (p < pend) {
			    if (RB_TYPE_P(*p, T_STRING) && RSTRING_PTR(*p) == t) {
				tmp = *p;
				break;
			    }
			    p++;
			}
			if (p == pend) {
			    rb_raise(rb_eArgError, "non associated pointer");
			}
		    }
		    UNPACK_PUSH(tmp);
		}
	    }
	    break;

	  case 'w':
	    {
                char *s0 = s;
                while (len > 0 && s < send) {
                    if (*s & 0x80) {
                        s++;
                    }
                    else {
                        s++;
                        UNPACK_PUSH(rb_integer_unpack(s0, s-s0, 1, 1, INTEGER_PACK_BIG_ENDIAN));
                        len--;
                        s0 = s;
                    }
                }
	    }
	    break;

	  default:
	    rb_warning("unknown unpack directive '%c' in '%s'",
		type, RSTRING_PTR(fmt));
	    break;
	}
    }

    return ary;
}

#upcase ⇒ `String`

Returns a copy of str with all lowercase letters replaced with their uppercase counterparts. The operation is locale insensitive—only characters “a” to “z” are affected. Note: case replacement is effective only in ASCII region.

"hEllO".upcase   #=> "HELLO"

Returns:

(String)

# File 'string.c', line 5113

static VALUE
rb_str_upcase(VALUE str)
{
    str = rb_str_dup(str);
    rb_str_upcase_bang(str);
    return str;
}

#upcase! ⇒ `String`^?

Upcases the contents of str, returning nil if no changes were made. Note: case replacement is effective only in ASCII region.

Returns:

(String, nil)

# File 'string.c', line 5048

static VALUE
rb_str_upcase_bang(VALUE str)
{
    rb_encoding *enc;
    char *s, *send;
    int modify = 0;
    int n;

    str_modify_keep_cr(str);
    enc = STR_ENC_GET(str);
    rb_str_check_dummy_enc(enc);
    s = RSTRING_PTR(str); send = RSTRING_END(str);
    if (single_byte_optimizable(str)) {
	while (s < send) {
	    unsigned int c = *(unsigned char*)s;

	    if (rb_enc_isascii(c, enc) && 'a' <= c && c <= 'z') {
		*s = 'A' + (c - 'a');
		modify = 1;
	    }
	    s++;
	}
    }
    else {
	int ascompat = rb_enc_asciicompat(enc);

	while (s < send) {
	    unsigned int c;

	    if (ascompat && (c = *(unsigned char*)s) < 0x80) {
		if (rb_enc_isascii(c, enc) && 'a' <= c && c <= 'z') {
		    *s = 'A' + (c - 'a');
		    modify = 1;
		}
		s++;
	    }
	    else {
		c = rb_enc_codepoint_len(s, send, &n, enc);
		if (rb_enc_islower(c, enc)) {
		    /* assuming toupper returns codepoint with same size */
		    rb_enc_mbcput(rb_enc_toupper(c, enc), s, enc);
		    modify = 1;
		}
		s += n;
	    }
	}
    }

    if (modify) return str;
    return Qnil;
}

#upto(other_str, exclusive = false) {|s| ... } ⇒ `String` #upto(other_str, exclusive = false) ⇒ `Object`

Iterates through successive values, starting at str and ending at other_str inclusive, passing each value in turn to the block. The String#succ method is used to generate each value. If optional second argument exclusive is omitted or is false, the last value will be included; otherwise it will be excluded.

If no block is given, an enumerator is returned instead.

"a8".upto("b6") {|s| print s, ' ' }
for s in "a8".."b6"
  print s, ' '
end

produces:

a8 a9 b0 b1 b2 b3 b4 b5 b6
a8 a9 b0 b1 b2 b3 b4 b5 b6

If str and other_str contains only ascii numeric characters, both are recognized as decimal numbers. In addition, the width of string (e.g. leading zeros) is handled appropriately.

"9".upto("11").to_a   #=> ["9", "10", "11"]
"25".upto("5").to_a   #=> []
"07".upto("11").to_a  #=> ["07", "08", "09", "10", "11"]

Overloads:

#upto(other_str, exclusive = false) {|s| ... } ⇒ String
Yields:
- (s)
Returns:
- (String)

# File 'string.c', line 3395

static VALUE
rb_str_upto(int argc, VALUE *argv, VALUE beg)
{
    VALUE end, exclusive;
    VALUE current, after_end;
    ID succ;
    int n, excl, ascii;
    rb_encoding *enc;

    rb_scan_args(argc, argv, "11", &end, &exclusive);
    RETURN_ENUMERATOR(beg, argc, argv);
    excl = RTEST(exclusive);
    CONST_ID(succ, "succ");
    StringValue(end);
    enc = rb_enc_check(beg, end);
    ascii = (is_ascii_string(beg) && is_ascii_string(end));
    /* single character */
    if (RSTRING_LEN(beg) == 1 && RSTRING_LEN(end) == 1 && ascii) {
	char c = RSTRING_PTR(beg)[0];
	char e = RSTRING_PTR(end)[0];

	if (c > e || (excl && c == e)) return beg;
	for (;;) {
	    rb_yield(rb_enc_str_new(&c, 1, enc));
	    if (!excl && c == e) break;
	    c++;
	    if (excl && c == e) break;
	}
	return beg;
    }
    /* both edges are all digits */
    if (ascii && ISDIGIT(RSTRING_PTR(beg)[0]) && ISDIGIT(RSTRING_PTR(end)[0])) {
	char *s, *send;
	VALUE b, e;
	int width;

	s = RSTRING_PTR(beg); send = RSTRING_END(beg);
	width = rb_long2int(send - s);
	while (s < send) {
	    if (!ISDIGIT(*s)) goto no_digits;
	    s++;
	}
	s = RSTRING_PTR(end); send = RSTRING_END(end);
	while (s < send) {
	    if (!ISDIGIT(*s)) goto no_digits;
	    s++;
	}
	b = rb_str_to_inum(beg, 10, FALSE);
	e = rb_str_to_inum(end, 10, FALSE);
	if (FIXNUM_P(b) && FIXNUM_P(e)) {
	    long bi = FIX2LONG(b);
	    long ei = FIX2LONG(e);
	    rb_encoding *usascii = rb_usascii_encoding();

	    while (bi <= ei) {
		if (excl && bi == ei) break;
		rb_yield(rb_enc_sprintf(usascii, "%.*ld", width, bi));
		bi++;
	    }
	}
	else {
	    ID op = excl ? '<' : rb_intern("<=");
	    VALUE args[2], fmt = rb_obj_freeze(rb_usascii_str_new_cstr("%.*d"));

	    args[0] = INT2FIX(width);
	    while (rb_funcall(b, op, 1, e)) {
		args[1] = b;
		rb_yield(rb_str_format(numberof(args), args, fmt));
		b = rb_funcall(b, succ, 0, 0);
	    }
	}
	return beg;
    }
    /* normal case */
  no_digits:
    n = rb_str_cmp(beg, end);
    if (n > 0 || (excl && n == 0)) return beg;

    after_end = rb_funcall(end, succ, 0, 0);
    current = rb_str_dup(beg);
    while (!rb_str_equal(current, after_end)) {
	VALUE next = Qnil;
	if (excl || !rb_str_equal(current, end))
	    next = rb_funcall(current, succ, 0, 0);
	rb_yield(current);
	if (NIL_P(next)) break;
	current = next;
	StringValue(current);
	if (excl && rb_str_equal(current, end)) break;
	if (RSTRING_LEN(current) > RSTRING_LEN(end) || RSTRING_LEN(current) == 0)
	    break;
    }

    return beg;
}

#valid_encoding? ⇒ `Boolean`

Returns true for a string which encoded correctly.

"\xc2\xa1".force_encoding("UTF-8").valid_encoding?  #=> true
"\xc2".force_encoding("UTF-8").valid_encoding?      #=> false
"\x80".force_encoding("UTF-8").valid_encoding?      #=> false

Returns:

(Boolean)

Returns:

(Boolean)

# File 'string.c', line 7931

static VALUE
rb_str_valid_encoding_p(VALUE str)
{
    int cr = rb_enc_str_coderange(str);

    return cr == ENC_CODERANGE_BROKEN ? Qfalse : Qtrue;
}

Class: String

Overview

Class Method Summary collapse

Instance Method Summary collapse

Equality.

Equality.

Methods included from Comparable

Constructor Details

#new(str = "") ⇒ String

Class Method Details

.try_convert(obj) ⇒ String?

Instance Method Details

#%(arg) ⇒ String

#*(integer) ⇒ String

#+(other_str) ⇒ String

#<<(integer) ⇒ String #concat(integer) ⇒ String #<<(obj) ⇒ String #concat(obj) ⇒ String

#<=>(other_string) ⇒ -1, ...

#==(obj) ⇒ Boolean #===(obj) ⇒ Boolean

Equality

#==(obj) ⇒ Boolean #===(obj) ⇒ Boolean

Equality

#=~(obj) ⇒ Fixnum?

#[]=(fixnum) ⇒ Object #[]=(fixnum, fixnum) ⇒ Object #[]=(range) ⇒ Object #[]=(regexp) ⇒ Object #[]=(regexp, fixnum) ⇒ Object #[]=(regexp, name) ⇒ Object #[]=(other_str) ⇒ Object

#ascii_only? ⇒ Boolean

#b ⇒ String

#bytes ⇒ Array

#bytesize ⇒ Integer

#byteslice(fixnum) ⇒ String? #byteslice(fixnum, fixnum) ⇒ String? #byteslice(range) ⇒ String?

#capitalize ⇒ String

#capitalize! ⇒ String?

#casecmp(other_str) ⇒ -1, ...

#center(width, padstr = ' ') ⇒ String

#chars ⇒ Array

#chomp(separator = $/) ⇒ String

#chomp!(separator = $/) ⇒ String?

#chop ⇒ String

#chop! ⇒ String?

#chr ⇒ String

#clear ⇒ String

#codepoints ⇒ Array

#<<(integer) ⇒ String #concat(integer) ⇒ String #<<(obj) ⇒ String #concat(obj) ⇒ String

#count([other_str]) ⇒ Fixnum

#crypt(salt_str) ⇒ String

#delete([other_str]) ⇒ String

#delete!([other_str]) ⇒ String?

#downcase ⇒ String

#downcase! ⇒ String?

#dump ⇒ String

#each_byte {|fixnum| ... } ⇒ String #each_byte ⇒ Object

#each_char {|cstr| ... } ⇒ String #each_char ⇒ Object

#each_codepoint {|integer| ... } ⇒ String #each_codepoint ⇒ Object

#each_line(separator = $/) {|substr| ... } ⇒ String #each_line(separator = $/) ⇒ Object

#empty? ⇒ Boolean

#encode(encoding[, options]) ⇒ String #encode(dst_encoding, src_encoding[, options]) ⇒ String #encode([options]) ⇒ String

#encode!(encoding[, options]) ⇒ String #encode!(dst_encoding, src_encoding[, options]) ⇒ String

#encoding ⇒ Encoding

#end_with?([suffixes]) ⇒ Boolean

#eql?(other) ⇒ Boolean

#force_encoding(encoding) ⇒ String

#freeze ⇒ Object

#getbyte(index) ⇒ 0 .. 255

#gsub(pattern, replacement) ⇒ String #gsub(pattern, hash) ⇒ String #gsub(pattern) {|match| ... } ⇒ String #gsub(pattern) ⇒ Object

#gsub!(pattern, replacement) ⇒ String? #gsub!(pattern) {|match| ... } ⇒ String? #gsub!(pattern) ⇒ Object

#hash ⇒ Fixnum

#hex ⇒ Integer

#include?(other_str) ⇒ Boolean

#index(substring[, offset]) ⇒ Fixnum? #index(regexp[, offset]) ⇒ Fixnum?

#replace(other_str) ⇒ String

#insert(index, other_str) ⇒ String

#inspect ⇒ String

#intern ⇒ Object #to_sym ⇒ Object

#length ⇒ Integer #size ⇒ Integer

#lines(separator = $/) ⇒ Array

#ljust(integer, padstr = ' ') ⇒ String

#lstrip ⇒ String

#lstrip! ⇒ self?

#match(pattern) ⇒ MatchData? #match(pattern, pos) ⇒ MatchData?

#succ ⇒ String #next ⇒ String

#succ! ⇒ String #next! ⇒ String

#oct ⇒ Integer

#new(str = "") ⇒ `String`

.try_convert(obj) ⇒ `String`^?

#%(arg) ⇒ `String`

#*(integer) ⇒ `String`

#+(other_str) ⇒ `String`

#<<(integer) ⇒ `String` #concat(integer) ⇒ `String` #<<(obj) ⇒ `String` #concat(obj) ⇒ `String`

#<=>(other_string) ⇒ `-1`, ...

#==(obj) ⇒ `Boolean` #===(obj) ⇒ `Boolean`

#==(obj) ⇒ `Boolean` #===(obj) ⇒ `Boolean`

#=~(obj) ⇒ `Fixnum`^?

#[]=(fixnum) ⇒ `Object` #[]=(fixnum, fixnum) ⇒ `Object` #[]=(range) ⇒ `Object` #[]=(regexp) ⇒ `Object` #[]=(regexp, fixnum) ⇒ `Object` #[]=(regexp, name) ⇒ `Object` #[]=(other_str) ⇒ `Object`

#ascii_only? ⇒ `Boolean`

#b ⇒ `String`

#bytes ⇒ `Array`

#bytesize ⇒ `Integer`

#byteslice(fixnum) ⇒ `String`^? #byteslice(fixnum, fixnum) ⇒ `String`^? #byteslice(range) ⇒ `String`^?

#capitalize ⇒ `String`

#capitalize! ⇒ `String`^?

#casecmp(other_str) ⇒ `-1`, ...

#center(width, padstr = ' ') ⇒ `String`

#chars ⇒ `Array`

#chomp(separator = $/) ⇒ `String`

#chomp!(separator = $/) ⇒ `String`^?

#chop ⇒ `String`

#chop! ⇒ `String`^?

#chr ⇒ `String`

#clear ⇒ `String`

#codepoints ⇒ `Array`

#<<(integer) ⇒ `String` #concat(integer) ⇒ `String` #<<(obj) ⇒ `String` #concat(obj) ⇒ `String`

#count([other_str]) ⇒ `Fixnum`

#crypt(salt_str) ⇒ `String`

#delete([other_str]) ⇒ `String`

#delete!([other_str]) ⇒ `String`^?

#downcase ⇒ `String`

#downcase! ⇒ `String`^?

#dump ⇒ `String`

#each_byte {|fixnum| ... } ⇒ `String` #each_byte ⇒ `Object`

#each_char {|cstr| ... } ⇒ `String` #each_char ⇒ `Object`

#each_codepoint {|integer| ... } ⇒ `String` #each_codepoint ⇒ `Object`

#each_line(separator = $/) {|substr| ... } ⇒ `String` #each_line(separator = $/) ⇒ `Object`

#empty? ⇒ `Boolean`

#encode(encoding[, options]) ⇒ `String` #encode(dst_encoding, src_encoding[, options]) ⇒ `String` #encode([options]) ⇒ `String`

#encode!(encoding[, options]) ⇒ `String` #encode!(dst_encoding, src_encoding[, options]) ⇒ `String`

#encoding ⇒ `Encoding`

#end_with?([suffixes]) ⇒ `Boolean`

#eql?(other) ⇒ `Boolean`

#force_encoding(encoding) ⇒ `String`

#freeze ⇒ `Object`

#getbyte(index) ⇒ `0 .. 255`

#gsub(pattern, replacement) ⇒ `String` #gsub(pattern, hash) ⇒ `String` #gsub(pattern) {|match| ... } ⇒ `String` #gsub(pattern) ⇒ `Object`

#gsub!(pattern, replacement) ⇒ `String`^? #gsub!(pattern) {|match| ... } ⇒ `String`^? #gsub!(pattern) ⇒ `Object`

#hash ⇒ `Fixnum`

#hex ⇒ `Integer`

#include?(other_str) ⇒ `Boolean`

#index(substring[, offset]) ⇒ `Fixnum`^? #index(regexp[, offset]) ⇒ `Fixnum`^?

#replace(other_str) ⇒ `String`

#insert(index, other_str) ⇒ `String`

#inspect ⇒ `String`

#intern ⇒ `Object` #to_sym ⇒ `Object`

#length ⇒ `Integer` #size ⇒ `Integer`

#lines(separator = $/) ⇒ `Array`

#ljust(integer, padstr = ' ') ⇒ `String`

#lstrip ⇒ `String`

#lstrip! ⇒ `self`^?

#match(pattern) ⇒ `MatchData`^? #match(pattern, pos) ⇒ `MatchData`^?

#succ ⇒ `String` #next ⇒ `String`

#succ! ⇒ `String` #next! ⇒ `String`

#oct ⇒ `Integer`

#ord ⇒ `Integer`

#partition(sep) ⇒ `Array` #partition(regexp) ⇒ `Array`

#prepend(other_str) ⇒ `String`

#replace(other_str) ⇒ `String`

#reverse ⇒ `String`

#reverse! ⇒ `String`

#rindex(substring[, fixnum]) ⇒ `Fixnum`^? #rindex(regexp[, fixnum]) ⇒ `Fixnum`^?

#rjust(integer, padstr = ' ') ⇒ `String`

#rpartition(sep) ⇒ `Array` #rpartition(regexp) ⇒ `Array`

#rstrip ⇒ `String`

#rstrip! ⇒ `self`^?

#scan(pattern) ⇒ `Array` #scan(pattern) {|match, ...| ... } ⇒ `String`