100之和（和上个代码类似）

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>

int main()//1 - 1/2 + 1/3 - 1/4 + 1/5 +...+1/99 - 1/100
{
int i;
double sum = 0;
double tmp = 0;
int flag = 1;
for (i = 1; i <= 100; i++){

   tmp = flag*1.0/i;//计算过程保存浮点型
   flag *= -1;
   sum += tmp;

}
printf("sum = %.11f\n", sum);

system("pause");
return 0;
}