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
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
  • Match everything enclosed
    (?:...)
  • Capture everything enclosed
    (...)
  • 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

/
/
gm

Test String

Code Generator

Generated Code

using System; using System.Text.RegularExpressions; public class Example { public static void Main() { string pattern = @/ ^<(?i)(?:input|textarea|\\w{0,}TextBox|\\w{0,}Field).*(?:name|id)=(?:\""|\')\w+(?:\""|\').* /; string input = @"{{! my-form.hbs }} <form onsubmit={{action ""submit""}}> <label for=""name"">Name:</label> <input type=""text"" id=""name"" value={{model.name}}> <label for=""email"">Email:</label> <input type=""email"" id=""email"" value={{model.email}}> <label for=""message"">Message:</label> <textarea id=""message"">{{model.message}}</textarea> <button type=""submit"">Submit</button> </form> <html> <head> <title>My Form</title> </head> <body> <form> <label for=""name"">Name:</label> <input type=""text"" name=""name"" id=""name""/> <label for=""email"">Email:</label> <input type=""email"" name=""email"" id=""email""/> <label for=""message"">Message:</label> <textarea name=""message"" id=""message""></textarea> <button type=""button"" onclick=""submitForm()"">Submit</button> </form> </body> </html>"; 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