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

$re = '/^(\w+?)$\n^(?=\1\:\w+?)/m'; $str = 'db_unknown cdbm01 oec0005u1 oec0008q1 oec0009q1 oec0015q1 oec0016q1 oec0205q1 oec0206q1 oec0209q1 oec0217q1 oec0218q1 oec0222q1 oec0224q1 oec0225q1 oec0282q1 oec0355q1 oec0374q1 oec0385q1 oec0388q1 oec0409q1 oec0419q1 oec0420q1 cdbm01 oec0005u1 oec0008q1 oec0009q1 oec0015q1 oec0016q1 oec0206q1 oec0209q1 oec0225q1 oec0374q1 oec0385q1 oec0388q1 oec0409q1 oekngtest1 oec0355q1 oec0462q2 oec0463q2 oec0464q2 oec0482q2 oec0496q2 oec0497q2 oec0499q2 oec0506q2 oec0511q2 oec0519q2 oec0529q2 oec0547q2 oec0553q2 oec0555q2 oec0667q2 oec0670q2 db1db2 db1db2 oec0462q2 oec0463q2 oec0464q2 oec0482q2 oec0496q2 oec0497q2 oec0499q2 oec0506q2 oec0511q2 oec0519q2 oec0529q2 oec0547q2 oec0553q2 oec0555q2 oec0667q2 oec0670q2 '; preg_match_all($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