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

/
/
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#"(?:(?<=@import\s*(['"]|url\()\s*)((?:\S|\\\1)+)\s*(?:\1|\))\s*\)?\s?(.*?);)"#).unwrap(); let string = "# Drupal core/tests/Drupal/Tests/Core/Asset/css_test_files/css_input_with_import.css @import \"import1.css\"; @import \"import2.css\"; @import url(\"http://example.com/style.css\"); @import url(\"//example.com/style.css\"); # Examples from https://developer.mozilla.org/en-US/docs/Web/CSS/%40import @import url(\"finep;rint.css\") print; @import url(\"bluish.;css\") projection, tv; @import 'cust;om.css'; @import url(\"chrome://communi;cator/skin/\"); @import \"common.css\" screen, projection; @import url('landscape.css') screen and (orientation:landscape); # Examples using htmlentities @import 'https://fonts.googleapis.com/css?family=Sedgwick+Ave+Display&amp;subset=latin-ext'; @import \"https://fonts.googleapis.com/css?family=Sedgwick+Ave+Display&amp;subset=latin-ext\" ; @import url(\"https://fonts.googleapis.com/css?family=Sedgwick+Ave+Display&amp;subset=latin-ext\"); @import url(\"https://fonts.googleapis.com/css?family=Sedgwick+Ave+Display&amp;subset=latin-ext\") tv; @import url(\"https://fonts.googleapis.com/css?family=Sedgwick+Ave+Display&amp;subset=latin-ext\") only screen and (max-width:639px) and (orientation: portrait); # Additional @import \"cu'st;om.css\"; @import \"cu\\\"st;om.css\"; @import \"cu\\22st;om.css\"; @import 'cus\\'t;om.css'; @import 'cus\\27t;om.css' ; @import 'cus(t;om.css' ; @import 'cus)t;om.css'; @import 'cus(t);om.css'; @import url( \" http://user:pass@example.com/c'u(s)t;o\\\"m.css \" ) ; @import url( ' http://user:pass@example.com/c\"u(s)t;o\\'m.css ' ) ; @import url( http://user:pass@example.com/c\\'u\\(s\\)t;om.css ) ; # Inline @import \"cu'st;om.css\"; @import \"cu\\\"st;om.css\"; .my-class { display: block; } @import \"cu'st;om.css\";@import url( \" http://user:pass@example.com/c'u(s)t;o\\\"m.css \" ) ;.some-class { color: rgba(0, 0, 0); }@import url( http://user:pass@example.com/c\\'u\\(s\\)t;om.css ) ;.some-class { color: rgba(0, 0, 0); } "; // 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/