Regular Expressions 101

Save & Share

Flavor

  • PCRE2 (PHP >=7.3)
  • PCRE (PHP <7.3)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java 8
  • .NET 7.0 (C#)
  • Rust
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests

Tools

Sponsors
There are currently no sponsors. Become a sponsor today!
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 = '/(?:(?:Sun|Mon|Tue|Wed|Thu|Fri|Sat),)?\s*([0-9]{2})(?:\s+|-)([Jj][Aa][Nn]|[Ff][Ee][Bb]|[Mm][Aa][Rr]|[Aa][Pp][Rr]|[Mm][Aa][Yy]|[Jj][Uu][Nn]|[Jj][Uu][Ll]|[Aa][Uu][Gg]|[Ss][Ee][Pp]|[Oo][Cc][Tt]|[Nn][Oo][Vv]|[Dd][Ee][Cc])(?:\s+|-)([0-9][0-9]([0-9][0-9])?)\s+(?:([01][0-9]|[2][0-3])):([0-5][0-9]):([0-5][0-9])\s*(?:GMT)?/'; $str = 'Wed, 23-May-12 01:23:31 GMT 23-May-12 01:23:31 GMT 23-May-12 01:23:31 23 May 2012 01:23:31 GMT 23 May 2012 01:23:31 GMT Wed, 23 May 2012 01:23:31 GMT 23 mAy 2012 01:23:31 GMT 23 maY 12 01:23:31 23 jan 12 22:23:31 01 AUG 12 15:23:31 GMT 01 bla 12 15:23:31 GMT 1 May 2012 15:23:31 GMT 01 May 2012 15:23:31 BLA 01 May 2012-15:23:31 01 May 2012-15/23:31 01 May 2012-15/23:31'; preg_match_all($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