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 $str = ' 1. Valid double-quoted strings: - "Hello" - "This is a test" - "123" - "Special characters: @#$%^&*()_+" - "Escape sequence: \\n" 2. Valid double-quoted strings with additional characters or variables: - " test aaaaa \\" " + asdf - " test " + ( "aaaaa" ) + gdf - " test \\" " + `" aaaa " + dfg - " test \' aaaaa \\" " + dfg - "" 3. Valid double-quoted strings with special characters: - "sas\'\'as\\"a1\\\'2 ! -_?:sa" - "\'\'" - "\\abnb\\ajhgf\\crt098& \\"\'" 4. Invalid double-quoted strings: - " test " + ( "aaaaa" ) \\" saf - "\\\\ + \\* test " \\$ \\. dsdfs - (\\" test \\" " + " aaaa " sfgd - \' test \' + aas ( "aaaaa" ) + \'\\ sd - \'\\\\ + \\* test \' \\$ \\. trace - (\' test \' as \' + \' aaaa \' - \'""\' - \'"sas\' - \'ads\' - \'asdasd\\"asdsa\' - "klkl"klkl - "asa\\\'sasa\\\\" - \\\'\\\\\\\' - "hhhh"klkl" - \'jkjkjk\'klklk\' - \'\\"\\\\\\"\' - \'\' - \'\\"asa\\\'sasa\\\\\\"\' - "sasasasa\\\\\\\\\\\\" 1. Valid single-quoted strings: - \'Hello\' - \'This is a test\' - \'123\' - \'Special characters: @#$%^&*()_+\' - \'Escape sequence: \\n\' 2. Valid single-quoted strings with additional characters or variables: - \' test aaaaa \\\' \' + asdf - \' test \' + ( \'aaaaa\' ) + gdf - \' test \\\' \' + \' aaaa\' + dfg - \' test " aaaaa \\\' \' + dfg - \'\' 3. Valid single-quoted strings with special characters: - \'sas""as\\\'a1\\"2 ! -_?:sa\' - \'""\' - \'\\abnb\\ajhgf\\crt098& \\\'""\' 4. Invalid single-quoted strings: - \' test \' + ( \'aaaaa\' ) \\\' saf - \'\\\\ + \\* test \' \\$ \\. dsdfs - (\\\' test \\\' + \' aaaa \' sfgd - " test \\" " + " aaaa " sfgd - \' test \' + aas ( \'aaaaa\' ) + \'\\ sd - \'\\\\ + \\* test \' \\$ \\. trace - (\' test \' as \' + \' aaaa \' - "\'\'" - \'sas" - "ads\' - \'asdasd\\\'asdsa\' - "klkl"klkl - "asa\\\'sasa\\\\" - \\\'\\\\\\\' - \'hhhh"klkl\\\'\\ - \\\'jkjkjk"klklk\' - "\\\'\\\\\\\'" - \'\' - \'\\"asa\\\'sasa\\\\\\"\' - \'sasasasa\\\\\\\\\\\\\' '; my $regex = qr/(?:\"(?:(?<=\"(?=[^\n]))[^\n]+?(?=(?<!\\))(?=\"))?\")|(\B'(?:(?<='(?=[^\n]))[^\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