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>

intmain()

{

                intn = 0;

                intsum = 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");

                return0;

}

//求从1到n的阶乘和

#include<stdio.h>

#include<stdlib.h>

intmain()

{

                intn = 0;

                intret = 1;

                intsum = 0;

                scanf("%d", &n);

                for(inti = 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");

                return0;

}