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

/
/
gm

Test String

Code Generator

Language

Generated Code

using System; using System.Text.RegularExpressions; public class Example { public static void Main() { string pattern = @"^(?:https?:\/\/)((?:www\.)|(?:m\.))?soundcloud\.com\/[a-z0-9](?!.*?(-|_){2})[\w-]{1,23}[a-z0-9](?:\/.+)?$"; string input = @"Use only numbers, lowercase letters, underscores, or hyphens. Profile URLs must not start or end with an underscore or hyphen. Profile URLs must not have two consecutive underscores or hyphens. Profile URLs must be between 3 and 25 characters. http://www.soundcloud.com/fo http://www.soundcloud.com/foo https://m.soundcloud.com/abcd123 https://soundcloud.com/abcd123 https://soundcloud.com/ https://m.soundcloud.com/abcd123_l https://soundcloud.com/abcd123-l http://www.soundcloud.com/-abcd123 http://www.soundcloud.com/_abcd123 https://m.soundcloud.com/abcd123-_l https://m.soundcloud.com/abcd123--l https://m.soundcloud.com/1234567890123456789012345 https://m.soundcloud.com/12345678901234567890123456 https://m.soundcloud.com/1234567890123456789012345/fooo12;lkflkjlfjkljskljflks/ https://m.soundcloud.com/12345678901234567890123456/fooo http://www.m.soundcloud.com/abcdef"; 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