C++ <cfenv> - FE_DOWNWARD

The FE_DOWNWARD macro expands to a value of type int, which can be used with fesetround and fegetround functions to indicate downward rounding direction. Rounding x downward gives the largest possible value that is not greater than x.

Definition in the <cfenv> header file is:

• C++11

#define FE_DOWNWARD  /* 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_DOWNWARD macro.

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

#pragma STDC FENV_ACCESS ON

using namespace std;
 
int main (){
  //downward rounding direction mode
  fesetround(FE_DOWNWARD);

  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) = 10
rint(-5.2) = -6
rint(-5.8) = -6