C program to find factorial of a number

PROGRAM:

#include <stdio.h>

int main()

{

    int n, i;

    unsigned long long factorial = 1;

    printf("Enter an integer: ");

    scanf("%d",&n);

    if (n < 0)

        printf("Error! Factorial of a negative number doesn't exist.");

    else

    {

        for(i=1; i<=n; ++i)

        {

            factorial *= i;              

        }

        printf("Factorial of %d = %llu", n, factorial);

    }

    return 0;

}

OUTPUT:

Enter an integer: 10

Factorial of 10 = 3628800