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  1. Prepare
  2. Python
  3. Regex and Parsing
  4. Validating Credit Card Numbers
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Validating Credit Card Numbers

  • andreypomortsev
     + 0 comments

    Self-documenting code is ostensibly written using human-readable names, typically consisting of a phrase in a human language which reflects the symbol's meaning, such as article.

    import re

def is_valid_credit_card(card_number: str) -> str:
    """Check if the card_number is valid or not,
    valid number has the following characteristics:
    It must start with a 4, 5 or 6.
    It must contain exactly 16 digits.
    It must only consist of digits (0-9).
    It may have digits in groups of 4, separated ONLY by one hyphen "-".
    It must NOT have 4 or more consecutive repeated digits.
    """
    pattern = re.compile(r'^(?!.*(\d)(-?\1){3})[456]\d{3}-?\d{4}-?\d{4}-?\d{4}$')
    if pattern.match(card_number):
        return "Valid"
    return "Invalid"

number_of_cards = int(input())
for _ in range(number_of_cards):
    card_to_check = input()
    print(is_valid_credit_card(card_to_check))