Regular Expressions 101

Save & Share

  • Current Version: 6
  • Update Regex
    ctrl+⇧+s
  • Save new Regex
    ctrl+s
  • Add to Community Library

Flavor

  • PCRE2 (PHP)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java
  • .NET 7.0 (C#)
  • Rust
  • PCRE (Legacy)
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests
Sponsors
There are currently no sponsors. Become a sponsor today!
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 = /\b\d+\s?(?:ff|f)+\.?(?=\s)/m str = '00f aaa + 00f. aaa + 00ff aaa + 00ff. aaa + 00 f aaa + 00 f. aaa aaa + 00 ff aaa + 00 ff. aaa + + aaa 00f aaa + + aaa 00f. aaa + + aaa 00ff aaa + + aaa 00ff. aaa + + aaa 00 f aaa + + aaa 00 f. aaa + + aaa 00 ff aaa + + aaa 00 ff. aaa + + aaa 00f + aaa 00f. + aaa 00ff + aaa 00ff. + aaa 00 f + aaa 00 f. + aaa 00 ff + aaa 00 ff. 00 faaa - 00 f.aaa - 00 ffaaa - 00 ff.aaa - 00af aaa - 00af. aaa - 00aff aaa - 00aff. aaa - - aaa 00 faaa - - aaa 00 f.aaa - - aaa 00 ffaaa - - aaa 00 ff.aaa - - aaa 00af aaa - - aaa 00af. aaa - - aaa 00aff aaa - - aaa 00aff. aaa - - aaa00f - aaa00f. - aaa00ff - aaa00ff. - aaa 00af - aaa 00af. - aaa 00aff - aaa 00aff. 00faaa - 00f.aaa - 00ffaaa - 00ff.aaa - 00af aaa - 00af. aaa - 00aff aaa - 00aff. aaa - - aaa00 faaa - - aaa00 f.aaa - - aaa00 ffaaa - - aaa00 ff.aaa - - aaa00af aaa - - aaa00af. aaa - - aaa00aff aaa - - aaa00aff. aaa - - aaa00af - aaa00af. - aaa00aff - aaa00aff.' subst = '' 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