C++ <cfenv> - FE_TONEAREST

The FE_TONEAREST macro expands to a value of type int, which can be used with fesetround and fegetround functions to indicate to-nearest rounding direction. Rounding x to-nearest gives the possible value that is nearest to x. For halfway cases, it is rounded away from zero.

Definition in the <cfenv> header file is:

• C++11

#define FE_TONEAREST  /* implementation defined */ 

All possible rounding direction modes are given below:

Certain library implementations may define additional floating-point rounding direction macro constants (with their corresponding macros also beginning with FE_).

Example:

The example below shows the usage of FE_TONEAREST macro.

#include <iostream>
#include <cfenv>
#include <cmath>

#pragma STDC FENV_ACCESS ON

using namespace std;
 
int main (){
  //to-nearest rounding direction mode
  fesetround(FE_TONEAREST);

  cout<<"rint(10.2) = "<<rint(10.2)<<"\n";
  cout<<"rint(10.8) = "<<rint(10.8)<<"\n";
  cout<<"rint(-5.2) = "<<rint(-5.2)<<"\n";
  cout<<"rint(-5.8) = "<<rint(-5.8)<<"\n";

  return 0;
}

The output of the above code will be:

rint(10.2) = 10
rint(10.8) = 11
rint(-5.2) = -5
rint(-5.8) = -6