C语言：求数列2,-4,6,-8,10,-12,...,前100项之和及第100项的值，咋编程？

Question

如题所述

Answer 1

代码文本：

#include "stdio.h"

int main(int argc,char *argv[]){

int n,i,s;

for(s=i=0,n=2;i<100;i++,n+=2)

s += i&1 ? -n : n;

printf("The sum are the %d\nThe last item is %d\n",s,(i&1 ? n-2 : 2-n));

return 0;

}