Factorial of a number

 #include <stdio.h>

int factorial(int a)

{

    if (a == 0 || a == 1)

    {

        return 1;

    }

    else

    {

        return (a * factorial(a - 1));

    }

}

int main()

{

    int num;

    printf("enter the number");

    scanf("%d", &num);

    printf("factorial of %d is %d", num, factorial(num));

    return 0;

}