Regular Expressions 101

Save & Share

  • Current Version: 2
  • 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

Code Generator

Language

Generated Code

import re regex = re.compile(r"(?P<browser>Android)\s(?P<major_version>\d+)\.(?P<minor_version>\d+\.?\d?);(?P<lang>\spt-br){0,1};{0,1}(?P<device>[ \w\-?]+)\s") test_str = ("20-03-2017 17:26:39\n" "GET /ourapps.php HTTP/1.1\n\n" "HTTP headers:\n" "Accept-Language: pt-BR,en-US;q=0.8\n" "Accept-Encoding: gzip, deflate\n" "User-Agent: Mozilla/5.0 (Linux; Android 5.1; 4017F Build/LMY47I; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/43.0.2357.121 Mobile Safari/537.36\n" "Accept: application/json, text/plain, */*\n" "Connection: close\n\n" "20-03-2017 20:17:08\n" "GET /ourapps.php HTTP/1.1\n\n" "HTTP headers:\n" "Accept-Charset: utf-8, iso-8859-1, utf-16, *;q=0.7\n" "Accept-Language: pt-BR, en-US\n" "Accept-Encoding: gzip,deflate\n" "X-Wap-Profile: http://gsm.lge.com/html/gsm/E467f-M3-D1.xml\n" "User-Agent: Mozilla/5.0 (Linux; U; Android 4.1.2; pt-br; LG-E467f Build/JZO54K) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30\n" "Accept: application/json, text/plain, */*\n" "Connection: close\n\n" "20-03-2017 21:09:36\n" "GET /ourapps.php HTTP/1.1\n\n" "HTTP headers:\n" "Accept-Language: pt-BR,en-US;q=0.8\n" "Accept-Encoding: gzip,deflate\n" "User-Agent: Mozilla/5.0 (Linux; Android 4.4.2; SM-G355M Build/KOT49H) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/30.0.0.0 Mobile Safari/537.36\n" "Accept: application/json, text/plain, */*\n" "Connection: close\n") matches = regex.finditer(test_str) for match_num, match in enumerate(matches, start=1): print(f"Match {match_num} was found at {match.start()}-{match.end()}: {match.group()}") for group_num, group in enumerate(match.groups(), start=1): print(f"Group {group_num} found at {match.start(group_num)}-{match.end(group_num)}: {group}")

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