Regular Expressions 101

Save & Manage Regex

  • Current Version: 13
  • Save & Share
  • 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
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

import re regex = re.compile(r"REVIEWDOG_VERSION(?:\s*=\s*|:?\s*)[\"|\']?v?\K\d+\.\d+(\.\d+)?(-[^\'\"\s]*)?", flags=re.MULTILINE) test_str = ("This is test file.\n\n" "REVIEWDOG_VERSION=v0.1.0\n" "REVIEWDOG_VERSION = v0.1.0\n" "REVIEWDOG_VERSION=0.1.0\n" "REVIEWDOG_VERSION = 0.1.0\n" "REVIEWDOG_VERSION=\"v0.1.0\"\n" "REVIEWDOG_VERSION='v0.1.0'\n" "REVIEWDOG_VERSION = \"v0.1.0\"\n" "REVIEWDOG_VERSION = 'v0.1.0'\n" "REVIEWDOG_VERSION=\"0.1.0\"\n" "REVIEWDOG_VERSION='0.1.0'\n" "REVIEWDOG_VERSION = \"0.1.0\"\n" "REVIEWDOG_VERSION = '0.1.0'\n" "REVIEWDOG_VERSION=\"v0.1.0-nightly20201208+12faa31\"\n" "REVIEWDOG_VERSION='v0.1.0-nightly20201208+12faa31'\n" "REVIEWDOG_VERSION = \"v0.1.0-nightly20201208+12faa31\"\n" "REVIEWDOG_VERSION = 'v0.1.0-nightly20201208+12faa31'\n" "REVIEWDOG_VERSION=\"0.1.0-nightly20201208+12faa31\"\n" "REVIEWDOG_VERSION='0.1.0-nightly20201208+12faa31'\n" "REVIEWDOG_VERSION = \"0.1.0-nightly20201208+12faa31\"\n" "REVIEWDOG_VERSION = '0.1.0-nightly20201208+12faa31'\n" "ENV REVIEWDOG_VERSION=0.1.0\n" "ENV REVIEWDOG_VERSION 0.1.0\n" "ARG REVIEWDOG_VERSION=0.1.0\n" "yaml:\n" " REVIEWDOG_VERSION: 0.1.0\n" " REVIEWDOG_VERSION: \"0.1.0\"\n" " REVIEWDOG_VERSION: '0.1.0'\n\n" "The above version should be updated to the latest version with this action.\n\n\n" "Other test cases.\n\n" "REDPEN_VERSION=1.10.1\n\n" "TMUX_VERSION=3.0\n") subst = "1.0.0-nightly23423423423423523gdsg" result = regex.sub(subst, test_str) if result: print(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 Python, please visit: https://docs.python.org/3/library/re.html