Rounding to 2 decimal points [duplicate]

Answer 1

This is because std::setprecision doesn't set the digits after the decimal point but the significant digits if you don't change the floating point format to use a fixed number of digits after the decimal point. To change the format, you have to put std::fixed into your output stream:

double a = 16.6;
std::cout << std::fixed << std::setprecision(2) << a << std::endl;

Answer 2

you can use printf / sprintf or other similar functions. Following code will format floating point value into two digits after decimals. Refer to the printf manual for more formatting info

float f = 1.234567
printf("%.2f\n", f);

Answer 3

From Trevor Boyd Smith's comment:

If you are allergic to printf and friends there is the type safe C++ version in #include <boost/format.hpp> which you can use to do:

float f = 1.234567;
cout << boost::format("%.2f") % f << endl;