Regular Expressions 101

Save & Manage Regex

  • Current Version: 1
  • 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

Code Generator

Language

Generated Code

import re regex = re.compile(r"\s+Content-[Tt]ype:\s*\S+") test_str = ("Accept-Ranges: bytes\n" "Cache-Control: max-age=604800\n" "Content-Type: text/html\n" "Date: Fri, 14 Aug 2015 17:45:05 GMT\n" "Etag: \"359670651\"\n" "Expires: Fri, 21 Aug 2015 17:45:05 GMT\n" "Last-Modified: Fri, 09 Aug 2013 23:54:35 GMT\n" "Server: ECS (fty/2FA4)\n" "X-Cache: HIT\n" "x-ec-custom-error: 1\n" "Content-Length: 1270\n\n\n" "- 0%[ ] 0 --.-KB/s <!doctype html>\n" "<html>\n" "<head>\n" " <title>Example Domain</title>\n\n" " <meta charset=\"utf-8\" />\n" " <meta http-equiv=\"Content-type\" content=\"text/html; charset=utf-8\" />\n" " <meta name=\"viewport\" content=\"width=device-width, initial-scale=1\" />\n" " <style type=\"text/css\">\n" " body {\n" " background-color: #f0f0f2;\n" " margin: 0;\n" " padding: 0;\n" " font-family: \"Open Sans\", \"Helvetica Neue\", Helvetica, Arial, sans-serif;\n" " \n" " }\n" " div {\n" " width: 600px;\n" " margin: 5em auto;\n" " padding: 50px;\n" " background-color: #fff;\n" " border-radius: 1em;\n" " }\n" " a:link, a:visited {\n" " color: #38488f;\n" " text-decoration: none;\n" " }\n" " @media (max-width: 700px) {\n" " body {\n" " background-color: #fff;\n" " }\n" " div {\n" " width: auto;\n" " margin: 0 auto;\n" " border-radius: 0;\n" " padding: 1em;\n" " }\n" " }\n" " </style> \n" "</head>\n\n" "<body>\n" "<div>\n" " <h1>Example Domain</h1>\n" " <p>This domain is established to be used for illustrative examples in documents. You may use this\n" " domain in examples without prior coordination or asking for permission.</p>\n" " <p><a href=\"http://www.iana.org/domains/example\">More information...</a></p>\n" "</div>\n" "</body>\n" "</html>") match = regex.search(test_str) if match: print(f"Match 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