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 single character of: a, b, c or d
    [[ab][cd]]
  • 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]
  • Character class intersection
    [\w&&[^\d]]
  • 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

"
"
g

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"([A-Z][a-z]+(\s[A-Z][a-z]+)*)").unwrap(); let string = "127.0.0.1 Amigo 30.08.2012 16:08:13 LOGIN OK 192.168.100.2 Vasya Pupkin 30.08.2012 16:08:40 DONE_TASK 15 OK 146.34.15.5 Eduard Petrovich Morozko 13.09.2013 5:04:50 DOWNLOAD_PLUGIN OK 127.0.0.1 Eduard Petrovich Morozko 11.12.2013 10:11:12 WRITE_MESSAGE FAILED 146.34.15.5 Eduard Petrovich Morozko 12.12.2013 21:56:30 WRITE_MESSAGE OK 146.34.15.5 Eduard Petrovich Morozko 03.01.2014 03:45:23 LOGIN OK 192.168.100.2 Vasya Pupkin 30.01.2014 12:56:22 SOLVE_TASK 18 ERROR 127.0.0.1 Vasya Pupkin 14.11.2015 07:08:01 WRITE_MESSAGE OK 192.168.100.2 Vasya Pupkin 19.03.2016 00:00:00 SOLVE_TASK 1 OK 146.34.15.5 Eduard Petrovich Morozko 05.01.2021 20:22:55 DONE_TASK 48 FAILED 127.0.0.1 Vasya Pupkin 14.10.2021 11:38:21 LOGIN OK 12.12.12.12 Amigo 21.10.2021 19:45:25 SOLVE_TASK 18 OK 120.120.120.122 Amigo 29.2.2028 5:4:7 SOLVE_TASK 18 OK"; // 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/