计算1-1/2+1/3-1/4+1/5 …… + 1/99 - 1/100的值

#include<stdio.h>

int main()
{
	double sum = 0.0;
	int flag = 1;
	int i = 1;
	for(i = 1;i <= 100; i ++)
	{
		sum = sum + (1.0/i)*flag;
		flag *= -1;     //flag=flag*(-1)
	}
	printf("%f\n",sum);
	return 0;
}

 

 

 

flag开关语句