C++级数逼近

求pi的近似值，精确到小数点后6位

#include <iostream>#include <iomanip> //与<<连用的设置方式#include <cmath>using namespace std;int main(){double sum=0, item=1;for(int n=1; abs(item)>1e-6; ++n){item *= (-1.0)*(2*n-3)/(2*n-1);sum += item;}cout<<"Pi = "<<setiosflags(ios::fixed)<<setprecision(6)<<sum*4<<endl;return 0;}