|HP-UX Reference > F
HP-UX 11i Version 3: February 2007
fetestexcept() — test floating-point exceptions
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.
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.
The fetestexcept() function returns the bitwise OR of the exception macros corresponding to the currently set floating-point exceptions included in excepts.
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();