no sugar - Regexp.new('pattern')
alternate form - %r{pattern}
normal regex - /pattern/iomx[neus]
options:
/i case insensitive
/o only interpolate #{} blocks once
/m multiline mode - '.' will match newline
/x extended mode - whitespace is ignored
/[neus] encoding: none, EUC, UTF-8, SJIS, respectively
regex characters:
. any character except newline
[ ] any single character of set
[^ ] any single character NOT of set
* 0 or more previous regular expression
*? 0 or more previous regular expression(non greedy)
+ 1 or more previous regular expression
+? 1 or more previous regular expression(non greedy)
? 0 or 1 previous regular expression
| alternation
( ) grouping regular expressions
^ beginning of a line or string
$ end of a line or string
{m,n} at least m but most n previous regular expression
{m,n}? at least m but most n previous regular expression(non greedy)
\A beginning of a string
\b backspace(0x08)(inside[]only)
\B non-word boundary
\b word boundary(outside[]only)
\d digit, same as[0-9]
\D non-digit
\S non-whitespace character
\s whitespace character[ \t\n\r\f]
\W non-word character
\w word character[0-9A-Za-z_]
\xHH hexadecimal char (encoded byte value)
\z end of a string
\Z end of a string, or before newline at the end
(?# ) comment
(?: ) grouping without backreferences
(?= ) zero-width positive look-ahead assertion
(?! ) zero-width negative look-ahead assertion
(?<= ) zero-width positive look-behind assertion
(?<! ) zero-width negative look-behind assertion
(?ix-ix) turns on/off i/x options, localized in group if any.
(?ix-ix: ) turns on/off i/x options, localized in non-capturing group.
(?<foo> ) named groups (only Ruby 1.9)
result of matching:
foo =~ /pattern/ # - if no match, returns nil.
- if match, returns positive integer position of first
matching character.
$& part of string matched by pattern.
$` part of string preceding match.
$' part of string after match.
Using named groups:
regex = %r(
^
b
(?<foo>
\w+
)
z
$
)x
m = 'barbaz'.match(regex)
m[:foo]
# => 'arba'
thanks to http://www.zenspider.com/Languages/Ruby/QuickRef.html#11
online regex checker links
--------------------
- for ruby http://www.rubular.com/
- for PHP PCRE,Posix, Javascript http://www.rexv.org/
- for Javascript with syntax highlighting http://regexpal.com/
