求n！

方法一：

#define _CRT_SECURE_NO_WARNINGS 1#include<stdio.h>#include<stdlib.h>#include<string.h>#include<windows.h>int Factorial(int n){    int i = 1;    int ret = 1;    for (; i <= n; i++)    {        ret *= i;    }    return ret;}int main(){    int num = 0;    printf("Please Enter a Number:>");    scanf("%d",&num);    printf("result = %d",Factorial(num));    system("pause");    return 0;}

方法二：

#define _CRT_SECURE_NO_WARNINGS 1#include<stdio.h>#include<stdlib.h>#include<string.h>//使用迭代方法int factorial(int num){    int result = 1;    while (num > 1)    {        result *= num;//从num开始乘        num--;    }    return result;}int main(){    int num = 0;    printf("请输入一个数:>");    scanf("%d",&num);    printf("result = %d",factorial(num));    system("pause");    return 0;}