NAME
fetestexcept() — test floating-point exceptions
SYNOPSIS
#include <fenv.h>
int fetestexcept(int excepts);
DESCRIPTION
The
fetestexcept()
function determines which of a specified subset of the floating-point
exception flags are currently set.
The
excepts
argument specifies the floating-point exception flags to be queried.
The argument can be constructed as a bitwise OR of the exception macros:
FE_INEXACT,
FE_DIVBYZERO,
FE_UNDERFLOW,
FE_OVERFLOW,
and
FE_INVALID.
FE_ALL_EXCEPT
represents all the floating-point exceptions.
USAGE
To use this function, compile either with the default
-Ae
option or with the
-Aa
and
-D_HPUX_SOURCE
options. Make sure your program includes
<fenv.h>.
For HP Integrity servers, specify
+Ofenvaccess
on the compiler command line or
place the call to this function under the effect of
an affirmative
FENV_ACCESS
pragma:
#pragma STDC FENV_ACCESS ON
If the
FENV_ACCESS
pragma is placed outside of any top-level
declarations in a file, the pragma will apply to all declarations in
the compilation following the pragma until another
FENV_ACCESS
pragma
is encountered or until the end of the file is reached.
If the
FENV_ACCESS
pragma is placed at the beginning of a block
(compound statement), the pragma will apply until another
FENV_ACCESS
pragma is encountered or until the end of the block is reached.
For PA-RISC, you might need to use the
+Onomoveflops
compiler option
in order to prevent optimizations that can undermine the specified behavior
of this function.
Link in the math library by specifying
-lm
on the compiler or linker command line.
For more information, see the
HP-UX floating-point guide for HP Integrity servers
at the following site:
http://www.hp.com/go/fp.
RETURN VALUE
The
fetestexcept()
function returns the bitwise OR of the exception macros corresponding
to the currently set floating-point exceptions included in
excepts.
ERRORS
No errors are defined.
EXAMPLES
Call
f()
if invalid is set, then
g()
if overflow is set:
#include <fenv.h>
/*...*/
int set_excepts;
/* operations that may raise exceptions */
set_excepts = fetestexcept(FE_INVALID | FE_OVERFLOW);
if (set_excepts & FE_INVALID) f();
if (set_excepts & FE_OVERFLOW) g();
STANDARDS CONFORMANCE
fetestexcept()
: ISO/IEC C99 (including Annex F, "IEC 60559 floating-point arithmetic")
Printable version
