add credit card validation tutorial

Author: x4nth055

README.md

@@ -223,6 +223,7 @@ This is a repository of all the tutorials of [The Python Code](https://www.thepy
     - [How to Make a Hangman Game in Python](https://www.thepythoncode.com/article/make-a-hangman-game-in-python). ([code](python-standard-library/hangman-game))
     - [How to Use the Argparse Module in Python](https://www.thepythoncode.com/article/how-to-use-argparse-in-python). ([code](python-standard-library/argparse))
     - [How to Make a Grep Clone in Python](https://thepythoncode.com/article/how-to-make-grep-clone-in-python). ([code](python-standard-library/grep-clone))
+    - [How to Validate Credit Card Numbers in Python](https://thepythoncode.com/article/credit-card-validation-in-python). ([code](python-standard-library/credit-card-validation))
 
 - ### [Using APIs](https://www.thepythoncode.com/topic/using-apis-in-python)
     - [How to Automate your VPS or Dedicated Server Management in Python](https://www.thepythoncode.com/article/automate-veesp-server-management-in-python). ([code](general/automating-server-management))

python-standard-library/credit-card-validation/README.md

@@ -0,0 +1 @@
+# [How to Validate Credit Card Numbers in Python](https://thepythoncode.com/article/credit-card-validation-in-python)

python-standard-library/credit-card-validation/credit_card_validation.py

@@ -0,0 +1,85 @@
+import argparse  # Import argparse for command-line argument parsing
+import re  # Import re for regular expression matching
+
+# Validate credit card number using Luhn Algorithm
+def luhn_algorithm(card_number):
+    def digits_of(n):
+        return [int(d) for d in str(n)]  # Convert each character in the number to an integer
+    
+    digits = digits_of(card_number)  # Get all digits of the card number
+    odd_digits = digits[-1::-2]  # Get digits from the right, skipping one digit each time (odd positions)
+    even_digits = digits[-2::-2]  # Get every second digit from the right (even positions)
+    
+    checksum = sum(odd_digits)  # Sum all odd position digits
+    for d in even_digits:
+        checksum += sum(digits_of(d*2))  # Double each even position digit and sum the resulting digits
+    
+    return checksum % 10 == 0  # Return True if checksum modulo 10 is 0
+
+
+# Function to check credit card number using Luhn's alogorithm
+def check_credit_card_number(card_number):
+    card_number = card_number.replace(' ', '')  # Remove spaces from the card number
+    if not card_number.isdigit():  # Check if the card number contains only digits
+        return False
+    return luhn_algorithm(card_number)  # Validate using the Luhn algorithm
+
+# Function to get the card type based on card number using RegEx
+def get_card_type(card_number):
+    card_number = card_number.replace(' ', '')  # Remove spaces from the card number
+    card_types = {
+        "Visa": r"^4[0-9]{12}(?:[0-9]{3})?$",  # Visa: Starts with 4, length 13 or 16
+        "MasterCard": r"^5[1-5][0-9]{14}$",  # MasterCard: Starts with 51-55, length 16
+        "American Express": r"^3[47][0-9]{13}$",  # AmEx: Starts with 34 or 37, length 15
+        "Discover": r"^6(?:011|5[0-9]{2})[0-9]{12}$",  # Discover: Starts with 6011 or 65, length 16
+        "JCB": r"^(?:2131|1800|35\d{3})\d{11}$",  # JCB: Starts with 2131, 1800, or 35, length 15 or 16
+        "Diners Club": r"^3(?:0[0-5]|[68][0-9])[0-9]{11}$",  # Diners Club: Starts with 300-305, 36, or 38, length 14
+        "Maestro": r"^(5018|5020|5038|56|57|58|6304|6759|676[1-3])\d{8,15}$",  # Maestro: Various starting patterns, length 12-19
+        "Verve": r"^(506[01]|507[89]|6500)\d{12,15}$"  # Verve: Starts with 5060, 5061, 5078, 5079, or 6500, length 16-19
+    }
+    
+    for card_type, pattern in card_types.items():
+        if re.match(pattern, card_number):  # Check if card number matches the pattern
+            return card_type
+    return "Unknown"  # Return Unknown if no pattern matches
+
+
+# Processing a file containing card numbers.
+def process_file(file_path):
+   
+    try:
+        with open(file_path, 'r') as file:  # Open the file for reading
+            card_numbers = file.readlines()  # Read all lines from the file
+        results = {}
+        for card_number in card_numbers:
+            card_number = card_number.strip()  # Remove any leading/trailing whitespace
+            is_valid = check_credit_card_number(card_number)  # Validate card number
+            card_type = get_card_type(card_number)  # Detect card type
+            results[card_number] = (is_valid, card_type)  # Store result
+        return results
+    except Exception as e:
+        print(f"Error reading file: {e}")  # Print error message if file cannot be read
+        return None
+
+
+def main():
+    parser = argparse.ArgumentParser(description="Check if a credit card number is legitimate and identify its type using the Luhn algorithm.")
+    parser.add_argument('-n', '--number', type=str, help="A single credit card number to validate.")  # Argument for single card number
+    parser.add_argument('-f', '--file', type=str, help="A file containing multiple credit card numbers to validate.")  # Argument for file input
+    
+    args = parser.parse_args()  # Parse command-line arguments
+    
+    if args.number:
+        is_valid = check_credit_card_number(args.number)  # Validate single card number
+        card_type = get_card_type(args.number)  # Detect card type
+        print(f"[!] Credit card number {args.number} is {'valid' if is_valid else 'invalid'} and is of type {card_type}.")  # Print result
+    
+    if args.file:
+        results = process_file(args.file)  # Process file with card numbers
+        if results:
+            for card_number, (is_valid, card_type) in results.items():
+                print(f"[!] Credit card number {card_number} is {'valid' if is_valid else 'invalid'} and is of type {card_type}.")  # Print results for each card number
+
+# Execute tha main function
+if __name__ == '__main__':
+    main()  

python-standard-library/credit-card-validation/credit_cards.txt

@@ -0,0 +1,3 @@
+4111111111111111
+5555555555554444
+378282246310005