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 = '/\b(?:(?=.{0,3}?\d)[A-Za-z\d]{4}\s??){3}\b/'; $str = '?K9X6 6GM6 LM11 // not recognized - but it should be !K9X6 6GM6 LM11 // not recognized - but it should be K0X6 0GM7 LM12! // not recognized - but it should be K1X6 1GM8 LM13@ // not recognized - but it should be K2X6 2GM9 LM14? // not recognized - but it should be K3X6 3GM0 LM15# // not recognized - but it should be K4X6 4GM1 LM16* // not recognized - but it should be K5X65GM2LM17 bla bla bla this shouldn\'t be visible spod also shouldn\'t be visible but line below should be!! K9X66GM6LM11! (see that "!" at the end? Help me with this) K5X65GM2LM17234324122323 //wrong, text is too long A9D24 A12E A59E3 //wrong, text block counts 5 characters! '; preg_match_all($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