求阶乘

迭代：

#include <stdio.h>
int main(void)
{
    int num;
    scanf("%d",&num);
    int result = 1;
    for (int i = 1; i <= num; i++)
    {
        result = result * i;
    }
    printf("%d! = %d\n",num,result); 
    return 0;    
}
>