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

# coding=utf8 # the above tag defines encoding for this document and is for Python 2.x compatibility import re regex = r""" (?# 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) """ test_str = ("# Based on data from https://www.freeformatter.com/credit-card-number-generator-validator.html\n\n" "# Currently only works for Visa, MasterCard, Discover, AmEx, JCB, Diners Club and only 16 digits (15 for AmEx, 14 for Diners Club Int'l)\n\n" "# VISA:\n" "4600259666104540\n" "4556-1328-5230-3974\n" "4485733989514555546\n" "# MasterCard:\n" "5288718104904007\n" "5183-2272-0427-5165\n" "2221001473307772\n" "# American Express (AMEX):\n" "379094106835131\n" "3767-607295-33484\n" "345614253532917\n" "# Discover:\n" "6011277600566135\n" "6011-7825-5703-7196\n" "6011621290066569622\n" "# JCB:\n" "3542928645179210\n" "3538837785961400\n" "3540948375054149466\n" "# Diners Club - North America:\n" "5440569380986811\n" "5500771351399605\n" "5555244536769443\n" "# Diners Club - Carte Blanche:\n" "30360146296936\n" "30381212693491\n" "30178078889506\n" "# Diners Club - International:\n" "36760821695498\n" "36861772048826\n" "36442207191455\n" "# Maestro:\n" "6759789245430267\n" "5893000324731008\n" "5038101669768864\n" "# Visa Electron:\n" "4026108950062250\n" "4913708902962931\n" "4844361267840716\n" "# InstaPayment:\n" "6370603085892230\n" "6390038329060763\n" "6395957073920994") matches = re.finditer(regex, test_str, re.MULTILINE | re.VERBOSE) for matchNum, match in enumerate(matches, start=1): print ("Match {matchNum} was found at {start}-{end}: {match}".format(matchNum = matchNum, start = match.start(), end = match.end(), match = match.group())) for groupNum in range(0, len(match.groups())): groupNum = groupNum + 1 print ("Group {groupNum} found at {start}-{end}: {group}".format(groupNum = groupNum, start = match.start(groupNum), end = match.end(groupNum), group = match.group(groupNum))) # Note: for Python 2.7 compatibility, use ur"" to prefix the regex and u"" to prefix the test string and substitution.

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 Python, please visit: https://docs.python.org/3/library/re.html