Regular Expressions 101

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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

/
/
g

Test String

Code Generator

Language

Generated Code

using System; using System.Text.RegularExpressions; public class Example { public static void Main() { string pattern = @"(?:https?:\/\/)?(?:www\.)?(?:youtu\.be\/|youtube\.com\/(?:embed\/|v\/|playlist\?|watch\?v=|watch\?.+(?:&|&#38;);v=))([a-zA-Z0-9\-_]{11})?(?:(?:\?|&|&#38;)index=((?:\d){1,3}))?(?:(?:\?|&|&#38;)?list=([a-zA-Z\-_0-9]{34}))?(?:\S+)?"; string input = @"https://www.youtube.com/playlist?list=PL1eC1aP-LYNg2ya1ywPj0pipd0y2EWGEl https://www.youtube.com/watch?v=4UcfECYbDYQ&index=1&list=PL1eC1aP-LYNg2ya1ywPj0pipd0y2EWGEl https://youtu.be/4UcfECYbDYQ?list=PL1eC1aP-LYNg2ya1ywPj0pipd0y2EWGEl https://www.youtube.com/watch?v=Svmor6ouuO4&index=4&list=PL1eC1aP-LYNg2ya1ywPj0pipd0y2EWGEl https://www.youtube.com/watch?v=M44e92KoIaE https://youtu.be/M44e92KoIaE https://www.youtube.com/embed/videoseries?list=PL1eC1aP-LYNg2ya1ywPj0pipd0y2EWGEl"; foreach (Match m in Regex.Matches(input, pattern)) { 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