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FEGETENV(3) Library Functions Manual FEGETENV(3)

fegetenv, feholdexcept, fesetenv, feupdateenvmanage floating-point environment

#include <fenv.h>

int
fegetenv(fenv_t *envp);

int
feholdexcept(fenv_t *envp);

int
fesetenv(const fenv_t *envp);

int
feupdateenv(const fenv_t *envp);

These functions manage the floating-point environment -- status flags, rounding direction modes and exception masks -- as one entity. The envp input argument is an object representing the floating-point environment. The macro FE_DFL_ENV represents the default floating-point environment -- the one installed at program startup.

The () function stores the current floating-point environment in the object pointed to by envp.

The () function saves the current floating-point environment in the object pointed to by envp, clears the floating-point status flags, and then installs a non-stop (continue on floating-point exceptions) mode for all floating-point exceptions.

The () function establishes the floating-point environment represented by the object pointed to by envp. The argument envp shall point to an object set by a call to fegetenv() or feholdexcept(), or equal the macro FE_DFL_ENV. Note that fesetenv() merely installs the state of the floating-point status flags represented through its argument, and does not raise these floating-point exceptions.

The () function saves the currently raised floating-point exceptions in its automatic storage, installs the floating-point environment represented by the object pointed to by envp, and then raises the saved floating-point exceptions. The argument envp shall point to an object set by a call to feholdexcept() or fegetenv(), or equal the macro FE_DFL_ENV.

The fegetenv(), feholdexcept(), fesetenv(), and feupdateenv() functions return zero on success, and non-zero if an error occurred.

feclearexcept(3), feenableexcept(3), fegetround(3)

The fegetenv(), feholdexcept(), fesetenv(), and feupdateenv() functions conform to ISO/IEC 9899:1999 (“ISO C99”).

The return types for fegetenv(), fesetenv(), and feupdateenv() are int for alignment with ISO/IEC 9899:1999 (“ISO C99”) Defect Report #202.

June 5, 2013 DragonFly-5.6.1