Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
No Match

/
/
gm

Test String

Code Generator

Language

Generated Code

use strict; my $str = 'print("Hello, world!") # this is a comment. print("The quick \\\\brown\\\\\\ndog\\rfox\\tjumps\\t over #the# /lazy/ \\"dog\\"###") # and here\'s where the real comment starts print("you can use Alt+0009 to enter a tab character!") # The above line had no comments, so the <comment> group didn\'t participate in the match. print("indented code") # with comment print("never indent code like this, but it still matches anyway")# comment lacking preceding whitespace >:) print("space indented code") print("Missing end quote print("unescaped \\") print("implicitly" " joined## " "string " "lit#erals") # a line can contain multiple string literals print("the quick " # line 1 "brown fox " # line 2 "jumps over " # line 3 "the lazy dog") # line 4 print("The quick brown", animal, "jumps over the", adjective, animal2, sep=" ") " print(\'Robert\'); DROP TABLE `Students`; -- \')'; my $regex = qr/^(?P<indentation>(?P<sp_or_tab>[ \t])*+)(?P<stmt>(?P<non_str_lit>(?:(?!\#)[^\"'\r\n])*?)(?:(?P<str_lit>(?P<begin_quote>(?P<single_quote>')|\")(?:(?(single_quote)\"|')|\\[\"']|\\[^\r\n ]|[^\"'\\\r\n])*?(?P=begin_quote))(?&non_str_lit))*?)(?P<whitespace>(?&sp_or_tab)*+)(?P<comment>(?:\#)[^\r\n]*+)?(?P<line_ending>\r|\n|\r\n)?$/mp; if ( $str =~ /$regex/g ) { print "Whole match is ${^MATCH} and its start/end positions can be obtained via \$-[0] and \$+[0]\n"; # print "Capture Group 1 is $1 and its start/end positions can be obtained via \$-[1] and \$+[1]\n"; # print "Capture Group 2 is $2 ... and so on\n"; } # ${^POSTMATCH} and ${^PREMATCH} are also available with the use of '/p' # Named capture groups can be called via $+{name}

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html