Regular Expressions 101

Save & Share

  • Regex Version: ver. 32
  • 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

r"
"
gim

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\.)?youtube(?:-nocookie)?\.com\/(?:v\/|e\/|embed\/|w\/|(?:watch\?v=|(?:(?:\?|watch\?)(?:[\w]+=[\w]+&?)+)v=)?|shorts\/)|youtu\.be\/(?:watch\?v=)?)([\w-]{11})(?=[^\w-]|$)(?![?=&+%\w.-]*(?:['\""][^<>]*>|<\/a>))[?=&+%\w.-]*$"; string input = @"thisdoesnotmatch seulement11 l_la5XiQJdk Qa5McwO3qY0 https://www.youtube.com/w/0tI4nOURzKI https://www.youtube.com/shorts/Qa5McwO3qY0 youtube.com/watch?v=vpiMAaPTze8 //youtu.be/DFYRQ_zQ-gk youtu.be/DFYRQ_zQ-gk http://www.youtube.com/watch?v=vpiMAaPTze8 http://youtu.be/l_la5XiQJdk http://youtu.be/NLqAF9hrVbY https://youtu.be/qT47KF5pvfw https://youtu.be/zImHyTyYhM8?t=4s https://youtu.be/DFYRQ_zQ-gk?t=120 https://youtu.be/DFYRQ_zQ-gk http://youtu.be/DFYRQ_zQ-gk //youtu.be/DFYRQ_zQ-gk http://www.youtube-nocookie.com/watch?v=NLqAF9hrVbY https://www.youtube.com/v/DFYRQ_zQ-gk?fs=1&hl=en_US http://www.youtube.com/v/DFYRQ_zQ-gk?fs=1&hl=en_US //www.youtube.com/v/DFYRQ_zQ-gk?fs=1&hl=en_US www.youtube.com/v/DFYRQ_zQ-gk?fs=1&hl=en_US youtube.com/v/DFYRQ_zQ-gk?fs=1&hl=en_US http://www.youtube.com/v/dQw4w9WgXcQ http://www.youtube.com/v/NLqAF9hrVbY?fs=1&hl=en_US http://www.youtube.com/embed/NLqAF9hrVbY https://www.youtube.com/embed/NLqAF9hrVbY http://www.youtube.com/embed/dQw4w9WgXcQ https://www.youtube.com/embed/DFYRQ_zQ-gk?autoplay=1 https://www.youtube.com/embed/DFYRQ_zQ-gk http://www.youtube.com/embed/DFYRQ_zQ-gk //www.youtube.com/embed/DFYRQ_zQ-gk www.youtube.com/embed/DFYRQ_zQ-gk https://youtube.com/embed/DFYRQ_zQ-gk http://youtube.com/embed/DFYRQ_zQ-gk //youtube.com/embed/DFYRQ_zQ-gk youtube.com/embed/DFYRQ_zQ-gk http://www.youtube.com/e/dQw4w9WgXcQ http://www.youtube.com/watch?v=NLqAF9hrVbY http://www.youtube.com/watch?v=spDj54kf-vY&feature=g-vrec http://www.youtube.com/watch?v=spDj54kf-vY&feature=youtu.be https://www.youtube.com/watch?v=MRl7cxSOXdU&feature=youtu.be https://www.youtube.com/watch?v=q07SQFmL4rM https://www.youtube.com/watch?v=q07SQFmL4yM https://www.youtube.com/watch?v=zImHyTyYhM8&t=4s http://www.youtube.com/watch?v=dQw4w9WgXcQ https://www.youtube.com/watch?v=DFYRQ_zQ-gk&feature=featured https://www.youtube.com/watch?v=DFYRQ_zQ-gk http://www.youtube.com/watch?v=DFYRQ_zQ-gk //www.youtube.com/watch?v=DFYRQ_zQ-gk www.youtube.com/watch?v=DFYRQ_zQ-gk http://www.youtube.com/watch?v=DFYRQ_zQ-gk //www.youtube.com/watch?v=DFYRQ_zQ-gk www.youtube.com/watch?v=DFYRQ_zQ-gk https://youtube.com/watch?v=DFYRQ_zQ-gk http://youtube.com/watch?v=DFYRQ_zQ-gk //youtube.com/watch?v=DFYRQ_zQ-gk youtube.com/watch?v=DFYRQ_zQ-gk https://www.youtube.com/watch?time_continue=4&v=zImHyTyYhM8 https://www.youtube.com/watch?v=zImHyTyYhM8 This working: https://www.youtube.com/watch?v=zImHyTyYhM8&time_continue=4& http://www.youtube.com/watch?feature=player_embedded&v=dQw4w9WgXcQ http://www.youtube.com/watch?v=dQw4w9WgXcQ&feature=player_embedded http://www.youtube.com/?feature=player_embedded&v=dQw4w9WgXcQ http://www.youtube.com/?aa=aa&bbb=bbb&cccc=cccc&v=dQw4w9WgXcQ http://www.youtube.com/?aa=aa&bbb=bbb&v=dQw4w9WgXcQ&cccc=cccc http://www.youtube.com/?aa=aa&v=dQw4w9WgXcQ&bbb=bbb&cccc=cccc https://m.youtube.com/watch?v=DFYRQ_zQ-gk http://m.youtube.com/watch?v=DFYRQ_zQ-gk //m.youtube.com/watch?v=DFYRQ_zQ-gk m.youtube.com/watch?v=DFYRQ_zQ-gk ------------------------------- All wrong urls ------------------------------------------------- http://www.youtube.com/user/username#p/u/11/dQw4w9WgXcQ http://www.youtube.com/sandalsResorts#p/c/54B8C800269D7C1B/0/dQw4w9WgXcQ http://www.youtube.com/user/Scobleizer#p/u/1/1p3vcRhsYGo http://www.youtube.com/ytscreeningroom?v=NRHVzbJVx8I http://www.youtube.com/sandalsResorts#p/c/54B8C800269D7C1B/2/PPS-8DMrAn4 http://gdata.youtube.com/feeds/api/videos/NLqAF9hrVbY https://www.youtube.com/HamdiKickProduction?v=DFYRQ_zQ-gk http://www.youtube.com/?v=dQw4w9WgXcQ http://www.youtube.com/&v=dQw4w9WgXcQ www.youtube.com/watch/ccc/ddd/DFYRQ_zQ-gk&feature=featured //www.youtube.com/vk/DFYRQ_zQwww //www.youtube.com/sdasdsadsd/DFYRQ_zQwww/fdfsdf/sdfsdfsdf www.youtube.com/awssssssss youtu.be/e/e/e/e/e/DFYRQ_zQwww/d/d/d/d/a/sfd/asd/as/DFYRQ_zQwww https://www.youtube.com/v=0tI4nOURzKI www.youtube.com/v=/DFYRQ_zQwww www.youtube.com/vDFYRQ_zQwww "; RegexOptions options = RegexOptions.IgnoreCase | 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