Reverses str in place.
Concatenates the given object(s) to str. If an object is an Integer, it is considered a codepoint and converted to a character before concatenation.
concat can take multiple arguments, and all the arguments are concatenated in order.
a = "hello " a.concat("world", 33) #=> "hello world!" a #=> "hello world!" b = "sn" b.concat("_", b, "_", b) #=> "sn_sn_sn"
See also String#<<, which takes a single argument.
Appends the given object to str. If the object is an Integer, it is considered a codepoint and converted to a character before being appended.
a = "hello " a << "world" #=> "hello world" a << 33 #=> "hello world!"
See also String#concat, which takes multiple arguments.
Prepend—Prepend the given strings to str.
a = "!" a.prepend("hello ", "world") #=> "hello world!" a #=> "hello world!"
See also String#concat.
Returns the string generated by calling crypt(3) standard library function with str and salt_str, in this order, as its arguments. Please do not use this method any longer. It is legacy; provided only for backward compatibility with ruby scripts in earlier days. It is bad to use in contemporary programs for several reasons:
* Behaviour of C's <code>crypt(3)</code> depends on the OS it is
run. The generated string lacks data portability.
* On some OSes such as Mac OS, <code>crypt(3)</code> never fails
(i.e. silently ends up in unexpected results).
* On some OSes such as Mac OS, <code>crypt(3)</code> is not
thread safe.
* So-called "traditional" usage of <code>crypt(3)</code> is very
very very weak. According to its manpage, Linux's traditional
<code>crypt(3)</code> output has only 2**56 variations; too
easy to brute force today. And this is the default behaviour.
* In order to make things robust some OSes implement so-called
"modular" usage. To go through, you have to do a complex
build-up of the <code>salt_str</code> parameter, by hand.
Failure in generation of a proper salt string tends not to
yield any errors; typos in parameters are normally not
detectable.
* For instance, in the following example, the second invocation
of <code>String#crypt</code> is wrong; it has a typo in
"round=" (lacks "s"). However the call does not fail and
something unexpected is generated.
"foo".crypt("$5$rounds=1000$salt$") # OK, proper usage
"foo".crypt("$5$round=1000$salt$") # Typo not detected
* Even in the "modular" mode, some hash functions are considered
archaic and no longer recommended at all; for instance module
<code>$1$</code> is officially abandoned by its author: see
http://phk.freebsd.dk/sagas/md5crypt_eol.html . For another
instance module <code>$3$</code> is considered completely
broken: see the manpage of FreeBSD.
* On some OS such as Mac OS, there is no modular mode. Yet, as
written above, <code>crypt(3)</code> on Mac OS never fails.
This means even if you build up a proper salt string it
generates a traditional DES hash anyways, and there is no way
for you to be aware of.
"foo".crypt("$5$rounds=1000$salt$") # => "$5fNPQMxC5j6."
If for some reason you cannot migrate to other secure contemporary password hashing algorithms, install the string-crypt gem and require 'string/crypt' to continue using it.
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
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 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 backslash 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 replacement is a String that looks like a pattern’s capture group but is actually not a pattern capture group e.g. "\'", then it will have to be preceded by two backslashes like so "\\'".
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.
"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?"
Returns a copy of str with 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 backslash 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*"
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 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"
Performs the same substitution as String#sub in-place.
Returns str if a substitution was performed or nil if no substitution was performed.
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.
Processes str as for String#chop, returning str, or nil if str is the empty string. See also String#chomp!.
Modifies str in place as described for String#chomp, returning str, or nil if no modifications were made.
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"
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"
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 \ can be used to escape ^ 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
Performs a delete operation in place, returning str, or nil if str was not modified.
Squeezes str in place, returning either str, or nil if no changes were made.
Returns a basic n-bit checksum of the characters in str, where n is the optional Integer parameter, defaulting to 16. The result is simply the sum of the binary value of each byte in str modulo 2**n - 1. This is not a particularly good checksum.
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 start 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
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"
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"]