Regular Expressions 101

Save & Manage Regex

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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
Processing...

Test String

Substitution
Processing...

Code Generator

Language

Generated Code

$re = '/([\n#*]+\s*)/m'; $str = '<!-- Comment 1 --> <!-- Comment 2 multiline Comment 2a Comment 2b--> <noinclude> {{draft}} [[Category:List by frequency]] </noinclude> == Inline == one # twor !! #two and half# L1phrase → L2 definition == List == # One # Two !! # Two and half # L1phrase → L2 definition # L1 item → L2 definition [pos:adjective, ipa: /vɜːt/] == Hidden pseudo JSON # 他 → { item:他, simplified:他, pinyin:tā, IPA:tʰa˥˥, eng:he }, # 我們 → { item:我們, simplified:我们, pinyin:wǒmen, IPA:uɔ˨˩mən, eng:we}, == Poems == *** INVICTUS (SENTENCES) Out of the night that covers me Black as the pit from pole to pole, I thank whatever gods may be For my unconquerable soul. In the fell clutch of circumstance, I have not winced nor cried aloud. Under the bludgeonings of chance My head is bloody, but unbowed. Beyond this place of wrath and tears Looms but the Horror of the shade, And yet the menace of the years Finds, and shall find, me unafraid. It matters not how strait the gate, How charged with punishments the scroll, I am the master of my fate I am the captain of my soul. INVICTUS (POEM MODE) Out of the night that covers me Black as the pit from pole to pole, I thank whatever gods may be For my unconquerable soul. In the fell clutch of circumstance, I have not winced nor cried aloud. Under the bludgeonings of chance My head is bloody, but unbowed. Beyond this place of wrath and tears Looms but the Horror of the shade, And yet the menace of the years Finds, and shall find, me unafraid. It matters not how strait the gate, How charged with punishments the scroll, I am the master of my fate I am the captain of my soul. '; $subst = "\n# "; $result = preg_replace($re, $subst, $str); echo "The result of the substitution is ".$result;

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