Regular Expressions 101

Save & Share

Flavor

  • PCRE2 (PHP >=7.3)
  • PCRE (PHP <7.3)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java 8
  • .NET 7.0 (C#)
  • Rust
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests

Tools

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
No Match

/
/
gm

Test String

Code Generator

Language

Generated Code

// include the latest version of the regex crate in your Cargo.toml extern crate regex; use regex::Regex; fn main() { let regex = Regex::new(r"(?m)([\w+]+\:\/\/)?([\w\d-]+\.)*[\w-]+[\(\)\#\.\:]\w+([\(\)\/\?\=\&\#\.]?[\w-]+)*\/?[\(\-\w\)\?\=\#_]*").unwrap(); let string = "https://daringfireball.net/2010/07/improved_regex_for_matching_urls Some of the advantages of the new pattern, compared to the previous one: It no longer uses the [:punct:] named character class. I thought this was universally supported in modern regex engines, but apparently it is not. It does a better job with URLs containing literal parentheses, correctly matching the following URLs that the previous pattern did not: .http://foo.com/more_(than)_one_(parens) http://foo.com/blah_(wikipedia)#cite-1. http://foo.com/blah_(wikipedia)_blah#cite-1. http://foo.com/unicode_(✪)_in_parens, http://foo.com/(something)?after=parens. It now matches mailto: URLs. It correctly guesses that things like “bit.ly/foo” and “is.gd/foo/” are URLs. Basically: something-dot-something-slash-something. teste www.google.com teste https://www.facebook.com. https://app-1.number123.com. http://facebook.com. ftp://facebook.com http://localhost:3000 localhost:3000/ unitedkingdomurl.co.uk this.is.a.url.com/its/still=going?wow shop.facebook.org app.number123.com app1.number123.com app-1.numbEr123.com app.dashes-dash.com www.facebook.com facebook.com fb.com/hello_123 fb.com/hel-lo fb.com/hello/goodbye fb.com/hello/goodbye?okay fb.com/hello/goodbye?okay=alright Hello www.google.com World http://yahoo.com https://www.google.com.tr/admin/subPage?qs1=sss1&qs2=sss2&qs3=sss3#Services https://google.com.tr/test/subPage?qs1=sss1&qs2=sss2&qs3=sss3#Services http://google.com/test/subPage?qs1=sss1&qs2=sss2&qs3=sss3#Services ftp://google.com/test/subPage?qs1=sss1&qs2=sss2&qs3=sss3#Services www.google.com.tr/test/subPage?qs1=sss1&qs2=sss2&qs3=sss3#Services www.google.com/test/subPage?qs1=sss1&qs2=sss2&qs3=sss3#Services drive.google.com/test/subPage?qs1=sss1&qs2=sss2&qs3=sss3#Services https://www.example.pl http://www.example.com www.example.pl example.com http://blog.example.com http://www.example.com/product http://www.example.com/products?id=1&page=2 http://www.example.com#up http://255.255.255.255 255.255.255.255 shop.facebook.org/derf.html Hello www.google.com World http://yahoo.com https://www.google.com.tr/admin/subPage?qs1=sss1&qs2=sss2&qs3=sss3#Services https://google.com.tr/test/subPage?qs1=sss1&qs2=sss2&qs3=sss3#Services http://google.com/test/subPage?qs1=sss1&qs2=sss2&qs3=sss3#Services ftp://google.com/test/subPage?qs1=sss1&qs2=sss2&qs3=sss3#Services www.google.com.tr/test/subPage?qs1=sss1&qs2=sss2&qs3=sss3#Services www.google.com/test/subPage?qs1=sss1&qs2=sss2&qs3=sss3#Services drive.google.com/test/subPage?qs1=sss1&qs2=sss2&qs3=sss3#Services Will match the following cases http://www.foufos.gr https://www.foufos.gr http://foufos.gr http://www.foufos.gr/kino http://werer.gr www.foufos.gr www.mp3.com www.t.co http://t.co http://www.t.co https://www.t.co www.aa.com http://aa.com http://www.aa.com https://www.aa.com Will NOT match the following www.foufos www.foufos-.gr www.-foufos.gr foufos.gr http://www.foufos http://foufos www.mp3#.com "; // result will be an iterator over tuples containing the start and end indices for each match in the string let result = regex.captures_iter(string); for mat in result { println!("{:?}", mat); } }

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 Rust, please visit: https://docs.rs/regex/latest/regex/