How do you detect Credit card type based on number?

Detecting Credit Card Type Based on Number

Credit card numbers follow specific patterns that can be used to identify the card type. Each type of credit card has a distinct prefix (also known as the Issuer Identification Number or IIN) and a specific length. Here’s how you can detect the credit card type based on the number.

Common Credit Card Types and Their Patterns

1. Visa

   • Starts with: 4
   • Length: 13, 16, 19

2. MasterCard

   • Starts with: 51 through 55 or 2221 through 2720
   • Length: 16

3. American Express

   • Starts with: 34 or 37
   • Length: 15

4. Discover

   • Starts with: 6011, 622126 through 622925, 644 through 649, 65
   • Length: 16, 19

5. Diners Club

   • Starts with: 300 through 305, 36, 38, 39
   • Length: 14

6. JCB

   • Starts with: 3528 through 3589
   • Length: 16

7. Maestro

   • Starts with: 50, 56 through 69
   • Length: 12 to 19

Implementation in Python

Here is a Python function to detect the credit card type based on the number:

import re

def get_credit_card_type(number):
    number = str(number)

    card_types = {
        "Visa": r"^4\d{12}(\d{3})?(\d{3})?$",
        "MasterCard": r"^(5[1-5]\d{4}|222[1-9]|22[3-9]\d{3}|2[3-6]\d{4}|27[01]\d{3}|2720)\d{10}$",
        "American Express": r"^3[47]\d{13}$",
        "Discover": r"^6(?:011|5\d{2}|4[4-9]\d|22[1-9]\d{1,2})\d{12}$",
        "Diners Club": r"^3(?:0[0-5]|[68]\d)\d{11}$",
        "JCB": r"^35(?:2[89]|[3-8]\d)\d{12}$",
        "Maestro": r"^(50|5[6-9]|6[0-9])\d{10,17}$"
    }

    for card_type, pattern in card_types.items():
        if re.match(pattern, number):
            return card_type

    return "Unknown"

# Example usage
print(get_credit_card_type("4111111111111111"))  # Output: Visa
print(get_credit_card_type("5500000000000004"))  # Output: MasterCard
print(get_credit_card_type("340000000000009"))   # Output: American Express
print(get_credit_card_type("6011000000000004"))  # Output: Discover
print(get_credit_card_type("30569309025904"))    # Output: Diners Club
print(get_credit_card_type("3530111333300000"))  # Output: JCB
print(get_credit_card_type("6759649826438453"))  # Output: Maestro

Explanation

1. Regex Patterns: The regular expressions (regex) for each card type are constructed based on their known prefixes and lengths.
2. Matching: The re.match function checks if the credit card number matches any of the card type patterns.
3. Return Type: The function returns the card type if a match is found, otherwise it returns "Unknown".

Summary

• Visa: Starts with 4, length 13, 16, or 19.
• MasterCard: Starts with 51-55 or 2221-2720, length 16.
• American Express: Starts with 34 or 37, length 15.
• Discover: Starts with 6011, 622126-622925, 644-649, 65, length 16 or 19.
• Diners Club: Starts with 300-305, 36, 38, 39, length 14.
• JCB: Starts with 3528-3589, length 16.
• Maestro: Starts with 50, 56-69, length 12-19.

By using regex patterns tailored to the specific prefixes and lengths of credit card numbers, you can reliably determine the type of credit card based on its number. For more in-depth knowledge and practical examples on programming concepts, consider exploring Grokking the Coding Interview on DesignGurus.io, which provides comprehensive courses on essential coding and interview techniques.