FEGETROUND(3P) POSIX Programmer's Manual FEGETROUND(3P)PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the corresponding
Linux manual page for details of Linux behavior), or the interface may
not be implemented on Linux.
fegetround, fesetround — get and set current rounding direction
int fesetround(int round);
The functionality described on this reference page is aligned with the
ISO C standard. Any conflict between the requirements described here
and the ISO C standard is unintentional. This volume of POSIX.1‐2008
defers to the ISO C standard.
The fegetround() function shall get the current rounding direction.
The fesetround() function shall establish the rounding direction repre‐
sented by its argument round. If the argument is not equal to the
value of a rounding direction macro, the rounding direction is not
The fegetround() function shall return the value of the rounding direc‐
tion 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 fesetround() function shall return a zero value if and only if the
requested rounding direction was established.
No errors are defined.
The following sections are informative.
The following example saves, sets, and restores the rounding direction,
reporting an error and aborting if setting the rounding direction
void f(int round_dir)
#pragma STDC FENV_ACCESS ON
save_round = fegetround();
setround_ok = fesetround(round_dir);
assert(setround_ok == 0);
/* ... */
/* ... */
The Base Definitions volume of POSIX.1‐2008, <fenv.h>
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
cal and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.unix.org/online.html .
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IEEE/The Open Group 2013 FEGETROUND(3P)