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

/
/

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"((19\d\d|20\d\d)-(0\d|1[0-2])-([0-2]\d|30|31))T((\d{2}):(\d{2}):(\d{2}))(?:\.(\d{3,6}))?(?:((?:([+-])(?:(0\d|1[012]))):?([0-5]\d))|Z?)").unwrap(); let string = "2008 2004-04-14 1997-01-27T18:57Z 2010-14-21T08:12:17.243+07:00 2010-12-21T08:12:17.243Z 2010-12-21T08:12:17.243 2010-11-21T08:12:17.243+07:00 2010-11-01T08:12:17.243+07:00 2010-12-11T08:12:17.243+0700 2010-01-21T08:12:17.243+07:00 2010-11-31T08:12:17.243+07:00 2010-14-21T08:12:17.243-37:00 2010-11-32T08:12:17.243+07:00 2010-14-21T08:12:17.243+0000 2010-14-21T08:12:17.243+1000 2010-11-21T08:12:17.243+0060 2010-14-21T08:12:17.243+1000 2010-14-21T08:12:17.243+1000 Non-Matches 3:00, 2/28/2003 2004-07-12 14:25:59 1900-01-01 00:00:00 9999-12-31 23:59:59 Non-Matches 04-07-12 14:25:59 20004-07-12 14:25 2004/07/12 14:25:59"; // result will be a tuple containing the start and end indices for the first match in the string let result = regex.captures(string); let (start, end) = match result { Some((s, e)) => (s, e), None => { // ... } }; println!("{}", &string[start, end]); }

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/