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
  • Match everything enclosed
    (?:...)
  • Capture everything enclosed
    (...)
  • 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

/
/
gmx

Test String

Code Generator

Generated Code

using System; using System.Text.RegularExpressions; public class Example { public static void Main() { string pattern = @/ (?# This regex was created for the purposes of detecting potentially compromised credentials for the purposes of information security and not to be used for malicious purposes.) (?<!\d) (?# s - Short [less than 16 digits], m - Medium [16 digits], l - Long [more than 16 digits; not yet implemented]) (?# First four digits) (?: (?# Standard 16 digit numbers) (?<m> (?#MasterCard between 222100-272099) 222[1-9]|223\d|2[3-6]\d{2}|27[01]\d|2720| (?#JCB is between 3528-3589) 352[89]|35[3-8]\d| (?#Visa, MasterCard, Discover) [4-6]\d{3} )| (?#American Express 15 digits | Diners Club 14 digits) (?<s>(?<ax>3[47]\d{2})|(?<dc>30[0-5]\d|36\d{2})) ) (?# Rest of the card number) (?<del>\D+)?(?(<m>)\d{4}(?(<del>)\k{del})\d{4}(?(<del>)\k{del})\d{4}|(?:\d{6})(?(<del>)\k{del})(?(<ax>)\d{5}|\d{4})) (?#END) (?!\d) /; string input = @"# Based on data from https://www.freeformatter.com/credit-card-number-generator-validator.html # Currently only works for Visa, MasterCard, Discover, AmEx, JCB, Diners Club and only 16 digits (15 for AmEx, 14 for Diners Club Int'l) # VISA: 4600259666104540 4556-1328-5230-3974 4485733989514555546 # MasterCard: 5288718104904007 5183-2272-0427-5165 2221001473307772 # American Express (AMEX): 379094106835131 3767-607295-33484 345614253532917 # Discover: 6011277600566135 6011-7825-5703-7196 6011621290066569622 # JCB: 3542928645179210 3538837785961400 3540948375054149466 # Diners Club - North America: 5440569380986811 5500771351399605 5555244536769443 # Diners Club - Carte Blanche: 30360146296936 30381212693491 30178078889506 # Diners Club - International: 36760821695498 36861772048826 36442207191455 # Maestro: 6759789245430267 5893000324731008 5038101669768864 # Visa Electron: 4026108950062250 4913708902962931 4844361267840716 # InstaPayment: 6370603085892230 6390038329060763 6395957073920994"; 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