1030-3-程序2-6.cpp

#include<stdio.h>
int main(){
	double sum = 0;
	for(int i = 0; ;i++)
	{
	double term = 1.0 / (i*2+1);
	if(i % 2==0)sum += term;
	else sum -= term;
	if(term< 1e-6) break;
	}
	printf("%.6f\n",sum);
	return 0;
}