求n的阶乘以及前n个数的阶乘和

//求n的阶乘

#include<stdio.h>

#include<stdlib.h>

int main()

{

                 int n = 0;

                 int sum = 1;

                scanf( "%d", &n);

                 while (n)                             //n如果为零，则不进入循环体，输出的sum初始值就是1

                {

                                sum *=n;

                                n--;

                }

                printf( "%d\n", sum);

                system( "pause");

                 return 0;

}

//求从1到n的阶乘和

#include<stdio.h>

#include<stdlib.h>

int main()

{

                 int n = 0;

                 int ret = 1;

                 int sum = 0;

                scanf( "%d", &n);

                 for (int i = 1; i <=n;i++)

                {

                                ret *= i;                             //ret是一直没有释放，从1的阶乘变到n的阶乘

                                sum += ret;

                }

                printf( "%d\n",sum);

                system( "pause");

                 return 0;

}