What is the role of **std::setprecision()** without **std::fixed** in c++?

Question

As shown in the tutorial http://www.cplusplus.com/reference/iomanip/setprecision/

// setprecision example
#include      // std::cout, std::fixed
         


        

Answer 1

Behaviour of std::setprecision() differs depending on the chosen formatting.

std::fixed make std::setprecision() refer to how many digits are printed after the decimal point. Before you change the default formatting to std::fixed, std::defaultfloat is set, and std::setprecision() sets the total number of digits to be printed, including the ones both before and after the decimal point.

Compare:

http://www.cplusplus.com/reference/ios/defaultfloat/

http://www.cplusplus.com/reference/ios/fixed/