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

Substitution

Processing...

Code Generator

Language

Generated Code

re = /([^. >"])([ ])?([-])?(<\/p>)\n.*?>/ str = '<p class="calibre1">pelled itself, riderless, in an endless orbit. </p> <p class="calibre1">The generator complex on the far side of this battlefield was </p> <p class="calibre1">intact, however. Reinforced concrete bunkers bristling with ma-</p> <p class="calibre1">chine guns surrounded a low building. The generators were deep </p> <p class="calibre1">beneath there. So far it looked as if the Covenant had not man-</p> <p class="calibre1">aged to take them, though not for lack of trying. </p> <p class="calibre1">"Contacts ahead," Joshua whispered. </p> <p class="calibre1">Four blips appeared on his motion sensor. Friend-or-foe tags </p> <p class="calibre1">identified them as UNSC Marines, Company Charlie. Serial </p> <p class="calibre1">numbers flashed next to the men as his HUD picked them out on a </p> <p class="calibre1">topo map of the area. </p> <p class="calibre1">Joshua handed Fred his sniper rifle, and he sighted the con-</p> <p class="calibre1">tacts through the scope. They were Marines, sure enough. They </p> <p class="calibre1">picked through the bodies that littered the area, looking for sur-</p> <p class="calibre1">vivors and policing weapons and ammo. </p> <p class="calibre1">Fred frowned; something about the way the Marine squad </p> <p class="calibre1">moved didn\'t feel right. They lacked unit cohesion, with their </p> <p class="calibre1">firstd, <i class="calibre4">you may as well drop with good intel. </i> </p> <p class="calibre1">Captain Keyes frowned on the ship\'s viewscreen, a </p> <p class="calibre1">"Roger that," he replied, "though I think I\'ve had enough surprises for one op." </p> <p class="calibre1">Kelly chuckled. </p>' subst = '$1$2' result = str.gsub(re, subst) # Print the result of the substitution puts 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 Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html