Saves the currently raised floating-point exceptions, restores the specified floating-point environment state, and then raises the saved floating-point exceptions.

int feupdateenv(  
   const fenv_t* penv  
);  

penv
Pointer to a fenv_t object that contains a floating-point environment as set by a call to fegetenv or feholdexcept. You can also specify the default startup floating-point environment by using the FE_DFL_ENV macro.

Returns 0 if all actions completed successfully. Otherwise, returns a nonzero value.

The feupdateenv function performs multiple actions. First, it stores the current raised floating-point exception status flags in automatic storage. Then, it sets the current floating-point environment from the value stored in the fenv_t object pointed to by penv. If penv is not FE_DFL_ENV or does not point to a valid fenv_t object, subsequent behavior is undefined. Finally, feupdateenv raises the locally stored floating-point exceptions.

To use this function, you must turn off floating-point optimizations that could prevent access by using the #pragma fenv_access(on) directive prior to the call. For more information, see fenv_access.

For additional compatibility information, see Compatibility.

fegetenv
feclearexcept
feholdexcept
fesetexceptflag