#include <stdio.h>
int facto(int);
int main()
{
    int n, a;
    printf("———————————————————————————————————————————");
    printf("\nProgram to find the factorial of a given number");
    printf("\n———————————————————————————————————————————");
    printf("\nEnter the number ");
    scanf("%d", &n);
    if (n < 0)
    {
        printf("Please enter a positive number or zero");
    }
    else if (n > 15)
    {
        printf("\nPlease enter a number less than 16");
    }
    else
    {
        a = facto(n);
        printf("\nThe factorial of %d is %d", n, a);
    }
    printf("\n———————————————————————————————————————————\n");
    return 0;
}
int facto(int n)
{
    int i, factorial = 1;
    for (i = 1; i <= n; i++)
    {
        factorial = factorial * i;
    }
    return (factorial);
}

codeaft@codeaft:~$ gcc codeaft.c
codeaft@codeaft:~$ ./a.out
———————————————————————————————————————————
Program to find the factorial of a given number
———————————————————————————————————————————
Enter the number 0

The factorial of 0 is 1
———————————————————————————————————————————

codeaft@codeaft:~$ ./a.out
———————————————————————————————————————————
Program to find the factorial of a given number
———————————————————————————————————————————
Enter the number 25

Please enter a number less than 16
———————————————————————————————————————————
codeaft@codeaft:~$