Regular Expressions 101

Save & Share

  • Regex Version: ver. 2
  • Update Regex
    ctrl+⇧+s
  • Save new Regex
    ctrl+s
  • Add to Community Library

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

using System; using System.Text.RegularExpressions; public class Example { public static void Main() { string pattern = @"^\s*at\s((?!webpack:).)*:\d+:\d+[\s\)]*\n"; string input = @" /src/components/compare/couples/index.jsx /Users/james/Work/nib/GithubEnterprise/frontend/react-static-example/src/components/compare/couples/index.jsx 23:5 error Parsing error: Unexpected token { ✖ 1 problem (1 error, 0 warnings) BabelLoaderError: SyntaxError: Unexpected token (23:4) 21 | const Couples = ({products}) => ( 22 | <div>%%>< > 23 | {Foobar} | ^ 24 | <Heading size=""1"">Couples</Heading> 25 | <img className=""banner"" src={img}/> 26 | <ul> at transpile (/Users/james/Work/nib/GithubEnterprise/frontend/react-static-example/node_modules/babel-loader/index.js:52:13) at /Users/james/Work/nib/GithubEnterprise/frontend/react-static-example/node_modules/babel-loader/lib/fs-cache.js:151:18 at ReadFileContext.callback (/Users/james/Work/nib/GithubEnterprise/frontend/react-static-example/node_modules/babel-loader/lib/fs-cache.js:29:23) at FSReqWrap.readFileAfterOpen [as oncomplete] (fs.js:303:13) static-react-render-webpack-plugin: Error rendering page ""scripts/components/compare/couples.js"": ReferenceError: Foobar is not defined at Couples (webpack:///./components/compare/couples/index.jsx?:37:5) at eval (webpack:///../~/react/lib/ReactCompositeComponent.js?:305:16) at measureLifeCyclePerf (webpack:///../~/react/lib/ReactCompositeComponent.js?:74:12) at ReactCompositeComponentMixin._constructComponentWithoutOwner (webpack:///../~/react/lib/ReactCompositeComponent.js?:304:14) at ReactCompositeComponentMixin._constructComponent (webpack:///../~/react/lib/ReactCompositeComponent.js?:279:21) at ReactCompositeComponentMixin.mountComponent (webpack:///../~/react/lib/ReactCompositeComponent.js?:187:21) at Object.ReactReconciler.mountComponent (webpack:///../~/react/lib/ReactReconciler.js?:47:35) at ReactDOMComponent.ReactMultiChild.Mixin.mountChildren (webpack:///../~/react/lib/ReactMultiChild.js?:240:44) at ReactDOMComponent.Mixin._createContentMarkup (webpack:///../~/react/lib/ReactDOMComponent.js?:661:32) at ReactDOMComponent.Mixin.mountComponent (webpack:///../~/react/lib/ReactDOMComponent.js?:528:29) "; RegexOptions options = RegexOptions.Multiline; foreach (Match m in Regex.Matches(input, pattern, options)) { Console.WriteLine("'{0}' found at index {1}.", m.Value, m.Index); } } }

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 C#, please visit: https://msdn.microsoft.com/en-us/library/system.text.regularexpressions.regex(v=vs.110).aspx