Using C Programming

For this project, you will implement a function that validates Visa credit card numbers. The function will take an unsigned long long int and return an int (or bool). A file is provided for you to complete. You only need to implement the function. You must match the function prototype given. You will receive a 0 if your function implementation does not match the given prototype. Do not add any global variables.

A valid Visa credit card has the following properties:

• starts with a 4
• is 16 digits long
• the Luhn algorithm results in a value that is a multiple of 10 (value % 10 = 0)

Here is a description of the Luhn algorithm using the number 4388576018402626.

1. Starting with the rightmost digit, add every other digit.

6 + 6 + 0 + 8 + 0 + 7 + 8 + 3 = 38

2. Double every other digit starting with the second digit from the right. If doubling of a digit results in a two-digit number, add the two digits to get a single-digit number.

2 * 2 = 4

2 * 2 = 4

4 * 2 = 8

1 * 2 = 2

6 * 2 = 12 (1 + 2 = 3)

5 * 2 = 10 (1 + 0 = 1)

8 * 2 = 16 (1 + 6 = 7)

4 * 2 = 8

Add all the single digit numbers.

4 + 4 + 8 + 2 + 3 + 1 + 7 + 8 = 37

3. Sum the results from Steps 2 and 3.

38 + 37 = 75

4. If the result from step 3 is divisible by 10, the credit card number is valid. Otherwise the number is invalid.

Use the below code to start:

#include

int isValidCC(unsigned long long int CCNumber);

int main()

{

unsigned long long int CCNumbers[] = {

4388576018410707ULL, // valid

4388576018402626ULL, // invalid

7388576018402686ULL, // invalid

438857601810707ULL, // invalid

4012888888881881ULL // valid

};

for (int i = 0; i < sizeof(CCNumbers) / sizeof(CCNumbers[0]); i++)

{

if (isValidCC(CCNumbers[i]))

{

printf("%llu is a valid Visa number. ", CCNumbers[i]);

}

else

{

printf("%llu is not a valid Visa number. ", CCNumbers[i]);

}

}

}

int isValidCC(unsigned long long int CCNumber)

{

// TO DO

}