//这里具体查一下digits10
setprecision(std::numeric_limits<long double>::digits10 + 1);
long double df = 45.222249999;
cout.setf(ios::showpoint
//这里具体查一下digits10
setprecision(std::numeric_limits<long double>::digits10 + 1);
long double df = 45.222249999;
cout.setf(ios::showpoint