#include <stdio.h>#include<math.h>int main(){? ?int sum = 0 , ?i = 1 , flag = 1;? ? while(i<=100)? ? { ? sum=sum+flag;? ? ? ? ? flag=i*pow((-1),i-1); //pow在這看不懂什么意思[ double pow(double x, double y);是求x的y次冪 ]? ? ? ? i++;? ? }? printf("sum=%d\n",sum);}