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 = @"^(.+)$(?=[\s\S]*^(\1)$[\s\S]*)"; string input = @" An HTML attachment was scrubbed... URL: https://list.something.edu/mailman/attachments/200908002/7452/attachment.html From SomeAddress at SomeDomain.org SomeDate From: SomeonesEmail at SomeDomain.org (FirstName LastName) Date: [the date] Subject: [ListservName] SomeSubject In-Reply-To: <SomeIDnumber> References: <%SomeEmailAddress> <SomeIDnumber> Message-ID: <SomeIDnumber> Hey there, Everyone, I completely disagree with this. It's crap! Sincerely, SomePerson On SomeDate, Someone wrote: From: SomeonesEmail at SomeDomain.org (FirstName LastName) Date: [the date] Subject: [ListservName] SomeSubject In-Reply-To: <SomeIDnumber> References: <%SomeEmailAddress> <SomeIDnumber> Message-ID: <SomeIDnumber> Hey PersonA, This is my advice. It is really good advice. I hope you take it since I think it's pertinent. Sincerely, PersonZ An HTML attachment was scrubbed... URL: https://list.something.edu/mailman/attachments/200908002/7452/attachment.html From SomeAdress at SomeDomain.org SomeDate From: SomeonesEmail at SomeDomain.org (FirstName LastName) Date: [the date] Subject: [ListservName] SomeSubject In-Reply-To: <SomeIDnumber> References: <%SomeEmailAddress> <SomeIDnumber> Message-ID: <SomeIDnumber> Good Afternoon, PersonA, But have you considered this aspect? It changes everything, so this is my advice. It is even better advice! Sincerely, PersonB On SomeDate, PersonZ wrote: Hey PersonA, This is my advice. It is really good advice. I hope you take it since I think it's pertinent. Sincerely, PersonZ From SomeAddress at SomeDomain.org SomeDate From: SomeonesEmail at SomeDomain.org (FirstName LastName) Date: [the date] Subject: [ListservName] SomeSubject In-Reply-To: <SomeIDnumber> References: <%SomeEmailAddress> <SomeIDnumber> Message-ID: <SomeIDnumber> Thank you all for your feedback on this issue. You've given me a lot to consider. Cheers. [And so on.] "; 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