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

/
/
g

Test String

Code Generator

Language

Generated Code

$re = '/"(\d+)"(?=[^{]*})/'; $str = 'i:0;s:2:"34";i:1;s:2:"35";a:29:{i:0;s:2:"34";i:1;s:2:"35";i:2;s:2:"37";i:3;s:2:"36";i:4;s:2:"38";i:5;s:2:"41";i:6;s:2:"33";i:7;s:2:"17";i:8;s:2:"20";i:9;s:2:"18";i:10;s:2:"19";i:11;s:2:"22";i:12;s:2:"23";i:13;s:2:"16";i:14;s:2:"21";i:15;s:2:"43";i:16;s:2:"70";i:17;s:2:"91";i:18;s:2:"50";i:19;s:2:"48";i:20;s:2:"49";i:21;s:2:"53";i:22;s:2:"47";i:23;s:2:"46";i:24;s:2:"44";i:25;s:3:"106";i:26;s:3:"121";i:27;s:2:"95";i:28;s:2:"86";};i:0;s:2:"34";i:1;s:2:"35";'; preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0); // Print the entire match result var_dump($matches);

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 PHP, please visit: http://php.net/manual/en/ref.pcre.php