FEUPDATEENV(3P) POSIX Programmer's Manual FEUPDATEENV(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.
NAMEfeupdateenv — update floating-point environment
SYNOPSIS
#include <fenv.h>
int feupdateenv(const fenv_t *envp);
DESCRIPTION
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 feupdateenv() function shall attempt to save the currently raised
floating-point exceptions in its automatic storage, attempt to install
the floating-point environment represented by the object pointed to by
envp, and then attempt to raise the saved floating-point exceptions.
The argument envp shall point to an object set by a call to feholdex‐
cept() or fegetenv(), or equal a floating-point environment macro.
RETURN VALUE
The feupdateenv() function shall return a zero value if and only if all
the required actions were successfully carried out.
ERRORS
No errors are defined.
The following sections are informative.
EXAMPLES
The following example shows sample code to hide spurious underflow
floating-point exceptions:
#include <fenv.h>
double f(double x)
{
#pragma STDC FENV_ACCESS ON
double result;
fenv_t save_env;
feholdexcept(&save_env);
// compute result
if (/* test spurious underflow */)
feclearexcept(FE_UNDERFLOW);
feupdateenv(&save_env);
return result;
}
APPLICATION USAGE
None.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSOfegetenv(), feholdexcept()
The Base Definitions volume of POSIX.1‐2008, <fenv.h>
COPYRIGHT
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 .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the source
files to man page format. To report such errors, see https://www.ker‐
nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 FEUPDATEENV(3P)
