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man pages section 3: Extended Library Functions, Volume 2

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Updated: Thursday, June 13, 2019
 
 

fesetround(3M)

Name

fegetround, fesetround - get and set current rounding direction

Synopsis

c99 [ flag... ] file... –lm [ library... ]
#include <fenv.h>

int fegetround(void);
int fesetround(int round);

Description

The fegetround() function gets the current rounding direction.

The fesetround() function establishes the rounding direction represented by its argument round. If the argument is not equal to the value of a rounding direction macro, the rounding direction is not changed.

Return Values

The fegetround() function returns the value of the rounding direction macro representing the current rounding direction, or a negative value if there is no such rounding direction macro or the current rounding direction is not determinable.

The fegetround() function returns a 0 value if and only if the requested rounding direction was established.

Errors

No errors are defined.

Examples

The following example saves, sets, and restores the rounding direction, reporting an error and aborting if setting the rounding direction fails:

Example 1 Save, set, and restore the rounding direction.
#include <fenv.h>
#include <assert.h>
void f(int round_dir)
{
      #pragma STDC FENV_ACCESS ON
      int save_round;
      int setround_ok;
      save_round = fegetround();
      setround_ok = fesetround(round_dir);
      assert(setround_ok == 0);
      /* ... */
      fesetround(save_round);
      /* ... */
}

Attributes

See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE
ATTRIBUTE VALUE
Interface Stability
Committed
Availability
system/library/math
MT-Level
MT-Safe
Standard

See Also

fenv.h(3HEAD), attributes(7), standards(7)