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

/
/
gmi

Test String

Code Generator

Language

Generated Code

using System; using System.Text.RegularExpressions; public class Example { public static void Main() { string pattern = @"{#include\s*([\w.]+)\s*}"; string input = @"{#include header.html} <header class=""bg-gradient-to-r from-purple-700 to-indigo-800 shadow-lg w-full""> <div class=""max-w mx-auto px-4 sm:px-6 lg:px-8 py-6""> <div class=""flex flex-col items-center justify-between md:flex-row""> <a href=""/""> <h1 class=""mb-4 text-2xl font-bold text-white md:mb-0 md:text-3xl"">Header</h1> </a> <nav class=""flex space-x-4""> <a href=""/""> <a href=""#"" class=""text-white transition duration-150 ease-in-out hover:text-purple-200"">Home</a> </a> <a href=""#"" class=""text-white transition duration-150 ease-in-out hover:text-purple-200"">About</a> <a href=""#"" class=""text-white transition duration-150 ease-in-out hover:text-purple-200"">Contact</a> </nav> </div> </div> </header> <div class=""flex flex-grow""> <aside class=""w-72 bg-gray-100 scrollable-column""> <div class=""p-6""> <h2 class=""mb-4 text-xl font-semibold text-gray-800"">Directories</h2> {#each item in dirs} <div class=""mb-3""> <a href=""{item.link}"" class=""font-medium text-indigo-600 transition duration-150 ease-in-out hover:text-indigo-800"">{item.name}</a> </div> {/each} </div> </aside> <main class=""flex-grow bg-white scrollable-column""> <div class=""p-6 md:p-8""> {#each item in files} <div class=""space-y-4""> <div class=""flex flex-col sm:flex-row border-b-2 border-gray-200 pb-4""> <div class=""w-full sm:w-[150px] h-[150px] border-2 border-black flex items-center justify-center overflow-hidden mb-4 sm:mb-0 flex-shrink-0""> <a href=""{item.link}""> <img src=""{item.image}"" alt=""thumbnail"" class=""w-full h-full object-cover""> </a> </div> <div class=""flex-grow pt-2 sm:pl-4""> <h3 class=""mb-2 text-xl font-semibold""> <a href=""{item.link}"" class=""text-indigo-600 transition duration-150 ease-in-out hover:text-indigo-800"">{item.name}</a> </h3> <p class=""text-black text-sm -mt-2 mb-2"">{item.date}</p> <p class=""text-gray-600 text-lg"">{item.summery}</p> </div> </div> </div> {/each} </div> </main> </div> <footer class=""bg-gray-800 text-white""> <div class=""container mx-auto px-4 py-8""> <div class=""flex flex-col items-center justify-between md:flex-row""> <div class=""mb-4 text-2xl font-semibold md:mb-0"">Footer</div> <div class=""flex space-x-4""> <a href=""#"" class=""transition duration-150 ease-in-out hover:text-purple-300"">Privacy</a> <a href=""#"" class=""transition duration-150 ease-in-out hover:text-purple-300"">Terms</a> <a href=""#"" class=""transition duration-150 ease-in-out hover:text-purple-300"">Contact</a> </div> </div> </div> </footer> {#include footer.html} "; RegexOptions options = RegexOptions.Multiline | RegexOptions.IgnoreCase; 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