fesetround()

Updated: October 26, 2022

Set the floating-point rounding direction

Synopsis:

#include <fenv.h>

int fesetround( int round );

Arguments:

round
The rounding direction; one of the following:
  • FE_DOWNWARD
  • FE_TONEAREST
  • FE_TOWARDZERO
  • FE_UPWARD

Library:

libm
The general-purpose math library.
libm-sve
(QNX Neutrino 7.1 or later) A library that optimizes the code for ARMv8.2 chips that have Scalable Vector Extension hardware.

Your system requirements will determine how you should work with these libraries:

Note: Compile your program with the -fno-builtin option to prevent the compiler from using a built-in version of the function.

Description:

The fesetround() function sets the current floating-point rounding direction. If the value of round isn't a valid rounding direction macro, the rounding direction isn't changed. The FLT_ROUNDS macro reflects the updated rounding direction.

Returns:

0 on success, or a nonzero value if an error occurred.

Classification:

C99, POSIX 1003.1

Safety:  
Cancellation point No
Interrupt handler Yes
Signal handler Yes
Thread Yes