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

/
/
gmx

Test String

Code Generator

Language

Generated Code

using System; using System.Text.RegularExpressions; public class Example { public static void Main() { string pattern = @"# Leap Years are any year that can be evenly divided by 4 # (such as 2012, 2016, etc) # • except if it can be evenly divided by 100 # then it isn't (such as 2100, 2200, etc) # • except if it can be evenly divided by 400, # then it is (such as 2000, 2400) # https://www.mathsisfun.com/leap-years.html # ------------------------------------------------- # verify date dd/mm/yyyy; possible separators: -.,/ # valid year range: 0000-9999 ^ # start anchor # precheck xx-xx-xxxx,... add new separators here (?=\d{2}([-.,\/])\d{2}\1\d{4}$) (?: # day-check: non caturing group # days 01-28 0[1-9]|1\d|[2][0-8]| # february 29d check for leap year: all 4y / 00 years: only each 400 # 0400,0800,1200,1600,2000,... 29 (?!.02. # not if feb: if not ... (?! # 00 years: exclude !0 %400 years (?!(?:[02468][1-35-79]|[13579][0-13-57-9])00) # 00,04,08,12,... \d{2}(?:[02468][048]|[13579][26]) ) )| # d30 negative lookahead: february cannot have 30 days 30(?!.02)| # d31 positive lookahead: month up to 31 days 31(?=.(?:0[13578]|10|12)) ) # eof day-check # month 01-12 .(?:0[1-9]|1[012]) # year 0000-9999 .\d{4} $ # end anchor"; string input = @"29/02/0000 29/02/0100 29/02/0200 29/02/0300 29/02/0400 29/02/0500 29/02/0600 29/02/0700 29/02/0800 29/02/0900 29/02/1000 29/02/1100 29/02/1200 29/02/1300 29/02/1400 29/02/1500 29/02/1600 29/02/1700 29/02/1800 29/02/1900 29/02/2000 29/02/2100 29/02/2200 29/02/2300 29/02/2400 29/02/2500"; RegexOptions options = RegexOptions.Multiline | RegexOptions.IgnorePatternWhitespace; 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