Sets the floating-point environment to a previously saved state, but preserves exceptions
#include <fenv.h> void feupdateenv ( const fenv_t *envp );
The feupdateenv( ) function internally saves the current floating-point exception status flags before installing the floating-point environment stored in the object referenced by its pointer argument. Then the function raises floating-point exceptions that were set in the saved status flags.
The argument must be a pointer to an object obtained by a prior call to fegetenv( ) or feholdexcept( ), or a macro such as FE_DFL_ENV, which is defined as a pointer to an object of type fenv_t representing the default floating-point environment.
The function returns 0 if successful; a nonzero return value indicates that an error occurred.
See the example for feholdexcept( ) in this chapter.