用循环求阶层

#include <stdio.h>
//求1!+2!+...+15!


int main(){
    double sum = 0;
    //求每个阶层的各

    int arg = 15;
    //阶层数

    int i;
    //控制每个阶

    for (i = 1; i <= arg ; i++){
        int jsum = 1;
        //jsum求阶,临时存阶层值

        int x;
        //控制下面的for循环

        for (x = 1; x <= i; x++){
         jsum *=x;
        }
        sum += jsum;
        printf("%2d 阶为 %8d \n",i,jsum);
    }
    printf("阶层积总和为: %f\n",sum);

return 0;
}

上面是写得思路比较简单和明了的,

下面只用一个循环来写,大家看看:

 

#include <stdio.h>
//?1!+2!+...+15!


int main(){
    double sum = 0;
    int arg = 15;
    int i;
    long int jsum = 1;
    for (i = 1; i <= arg ; i++){
        jsum *=i;
        //这里每乘一次都会得到一个阶层值.所以直接加就可以求和了
        sum += jsum;
        printf("fffff: %2d %8d \n",i,jsum);
    }
    printf("fffff: %18f\n",sum);

return 0;
}