How to use factorial number in C Language

#include <stdio.h>
int main()
{
    int n, num;
    long fact = 1;
    printf("enter a number : ");
    scanf("%d", &n);
    num = n;
    if (n < 0)
    {
        printf("no factorial of negative number\n");
    }
    else
    {
        while (n > 1)
        {
            fact *= n;
            n--;
        }
        printf("factorial of %d=%d\n", num, fact); 
    }
    return 0;
}