Credit Card Validator

A credit card validator is a program that validates the format of a credit card number. Credit card numbers are typically 16 digits long and follow a specific format. A credit card validator checks if the credit card number is valid based on the format and other criteria.

Syntax

bool is_valid_credit_card(string credit_card_number);

Here, is_valid_credit_card is a function that takes a string credit_card_number as input and returns a boolean value indicating whether the credit card number is valid or not.

Example

#include <iostream>
using namespace std;

bool is_valid_credit_card(string credit_card_number) {
    int sum = 0;
    bool is_second = false;

    for(int i = credit_card_number.size() - 1; i >= 0; i--) {
        int d = credit_card_number[i] - '0';

        if(is_second == true)
            d *= 2;

        sum += d / 10;
        sum += d % 10;

        is_second = !is_second;
    }

    return (sum % 10 == 0);
}

int main() {
    string credit_card_number = "4012888888881881";

    if(is_valid_credit_card(credit_card_number))
        cout << "Credit card number is valid" << endl;
    else
        cout << "Credit card number is not valid" << endl;

    return 0;
}

Output

Credit card number is valid

Explanation

In the above example, we have written a function is_valid_credit_card that takes a credit card number as input and returns true if the number is valid, and false otherwise. We have tested the function by passing a credit card number to it, and printing the output based on the return value.

The credit card number validation algorithm used in this example is known as the Luhn algorithm. It is a simple checksum formula used to validate credit card numbers.

Use

A credit card validator can be used to check if a credit card number is valid or not. This can be useful in e-commerce applications or any application that involves the use of credit cards for payment.

Important Points

• A credit card validator checks if a credit card number is valid based on its format and other criteria.
• The Luhn algorithm is commonly used to validate credit card numbers.
• The Luhn algorithm involves calculating a checksum over the digits of the credit card number.

Summary

In summary, a credit card validator is a program that checks if a credit card number is valid. The Luhn algorithm is a commonly used algorithm for credit card validation, which involves calculating a checksum over the digits of the credit card number. Credit card validation is important in e-commerce applications and other applications that involve the use of credit cards for payment.