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]
  • Character class intersection
    [\w&&[^\d]]
  • 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
Processing...

Test String

Code Generator

Language

Generated Code

import re regex = re.compile(r"\b6(?:011|5[0-9]{2})[ -]([0-9]{4}[ -]){2}([0-9]{4})\b|\b6(?:011|5[0-9]{2})[0-9]{12}\b", flags=re.MULTILINE) test_str = ("Discover\n\n" "Requirements: Discover cards start with the number 6011 or 65 and have 16 digits. \n\n" "Pattern Parts:\n" "Starts with number 6011 or 65, has 16 length, and has space or dash:\n" "1) \\b6(?:011|5[0-9]{2})[ -]([0-9]{4}[ -]){2}([0-9]{4})\\b\n\n" "Starts with number 6011 or 65, has 16 length, and has no space or dash:\n" "2) \\b6(?:011|5[0-9]{2})[0-9]{12}\\b\n\n" "Combining 1-2 to form one pattern:\n" "\\b6(?:011|5[0-9]{2})[ -]([0-9]{4}[ -]){2}([0-9]{4})\\b|\\b6(?:011|5[0-9]{2})[0-9]{12}\\b\n\n\n" "Test Cases:\n" "Positive (Should fire):\n" "16 length, no space, start with 6011 Here is the cc: 6011123412341234 Thanks.\n" "16 length, dashes, start with 6011 6011-1234-1234-1234\n" "16 length, spaces, start with 6011 6011 1234 1234 1234\n\n" "16 length, no space, start with 65 6521123412341234\n" "16 length, dashes, start with 65 6521-1234-1234-1234\n" "16 length, spaces, start with 65 6521 1234 1234 1234\n\n" "Embedded in sentence with space:\n" "16 length, no space, start with 6011 Here is the cc: 6011123412341234\n" "16 length, dashes, start with 6011 Here is the cc: 6011-1234-1234-1234\n" "16 length, spaces, start with 6011 Here is the cc: 6011 1234 1234 1234\n\n" "16 length, no space, start with 65 Here is the cc: 6521123412341234\n" "16 length, dashes, start with 65 Here is the cc: 6521-1234-1234-1234\n" "16 length, spaces, start with 65 Here is the cc: 6523 1234 1234 1234\n\n" "16 length, no space, start with 6011 Credit Card#:6011123412341234\n" "16 length, dashes, start with 6011 Credit Card#:6011-1234-1234-1234\n" "16 length, spaces, start with 6011 Credit Card#:6011 1234 1234 1234\n\n" "16 length, no space, start with 65 Credit Card#:6521123412341234\n" "16 length, dashes, start with 65 Credit Card#:6521-1234-1234-1234\n" "16 length, spaces, start with 65 Credit Card#:6523 1234 1234 1234\n\n" "Negative (Should Not Fire):\n" "16 length, no space, not start with 6011 6012123412341234\n" "16 length, dashes, not start with 6011 6012-1234-1234-1234\n" "16 length, spaces, not start with 6011 6012 1234 1234 1234\n\n" "16 length, no space, not start with 65 6612123412341234\n" "16 length, dashes, not start with 65 6612-1234-1234-1234\n" "16 length, spaces, not start with 65 6612-1234-1234-1234\n\n" "16 length, no space, start with 65, embedded Credit Card Number6521123412341234\n" "16 length, dashes, start with 6011, malformed 601-11234-1234-1234\n\n" "16 length num matching pattern but embedded User ID: 0000006011123412341234000000") matches = regex.finditer(test_str) for match_num, match in enumerate(matches, start=1): print(f"Match {match_num} was found at {match.start()}-{match.end()}: {match.group()}") for group_num, group in enumerate(match.groups(), start=1): print(f"Group {group_num} found at {match.start(group_num)}-{match.end(group_num)}: {group}")

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