/*  Random Credit Card Numbers (10 points)

Write a complete C program that generates 10 random 16-digit credit 
card numbers for a Discover card. The first 6 digits of each credit card 
number are reserved for the issuer number. For Discover cards these
digits must be "6011-xx". The remaining ten digits are the account number. 
Print the credit card numbers using the standard format: 6011-xxxx-xxxx-xxxx.
The card numbers must be different every time your program is executed. 
 
SAMPLE RUN:
	
6011-3834-4218-9357
6011-5536-3701-3912
6011-1663-8203-7559
6011-4510-8871-8681
6011-8568-2780-4730
6011-1436-1756-1762
6011-4189-3250-7716
6011-0609-1802-2561
6011-9681-8075-1019
6011-3003-5535-4391

*/ 

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main(void)
{
	int i, d;
	int n[12]; // an array to store the 12 random digits
	
	srand ( time(NULL) );  // initialize the random number generator

	for(i=0; i<10; i++) // ten numbers
	{
		for(d=0; d<12; d++) // generate twelve digits for each card number
			n[d] =  rand()%10;
		
		printf("6011-");   // print 1st 4 digits (always fixed)
		printf("%d%d%d%d-", n[0], n[1], n[2], n[3]); // print 2nd 4 digits
		printf("%d%d%d%d-", n[4], n[5], n[6], n[7]); // print 3rd 4 digits 
		printf("%d%d%d%d",  n[8], n[9],n[10],n[11]); // print 4th 4 digits
		printf("\n");
	}	
    system("pause");
}