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

r"
"
gm

Test String

Code Generator

Language

Generated Code

using System; using System.Text.RegularExpressions; public class Example { public static void Main() { string pattern = @"http://www\.xinhuanet\.com/yuqing/([0-9]*)-([0-9]*)/([0-9]*)/([a-z])_([0-9]*)\.htm"; string input = @"</li> <li class=""clearfix""> <h3><a href=""http://www.xinhuanet.com/yuqing/2015-10/25/c_128355180.htm"" target=""_blank"">张志安：优秀微信公众号发展离不开这12个字</a></h3> <i class=""imgs""><a href=""http://www.xinhuanet.com/yuqing/2015-10/25/c_128355180.htm"" targrt=""_blank""><img class=""lazyload"" src=""http://www.news.cn/images2014/xh_load.gif"" data-original="" /></a></i> <p class=""summary"">移动互联网的本质是通过便利的方式将内容连接起来，而优秀微信公众号正是用内容和服务在社群之间建立连接。回归一个起点，一个基本的逻辑，一个人有怎样的风格，这个人所带领的团队，所运营的微信公众号就有怎样的风格，风格是价值观的直接体现，也是这个公众号可持续发展的关键。</p> <div class=""info""> <div class=""bdsharebuttonbox clearfix""> </div> <span class=""time"">2015-10-25</span> </div> "; 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