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 = '/\[(b|i|u|h1|h2|h3|large|small|list|table|grid)\](?:((?!\[\/\1\]).)*?|(?R))*\[\/\1\]/m'; $str = '[b]the problem is that my [i]regex[/i] stops at the [b]first matching closing tag[/b] instead of matching recursively as i [u]expect it to.[/u] [/b] [i]regex[/i] stops at the [b]first matching closing tag[/b] instead of matching recursively as i [u]expect it to.[/u] [a]ssss[a]sssss[/a]ss[/a] [b]sss[/b] [c]asdfasd[d]asdaf[/d]fasdf[/c] [i]test test [i]as fd[/i]this should match the whole line[/i] [i]test test[j]this should match the whole line[/j]test[/i] [i] test [j]this should match the pair of \'i\' tags and ignore the second \'j\' tag [/i] [/j] the below line should have three sets of matches: center, h3, and grid; it only matches the h3 and grid tags [center][logo][/center][hr][hr][h3]header[/h3][/center][hr][hr][grid][row][cell][b]some label[/b][cell]: [date][/grid] '; preg_match_all($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