Sets the current floating-point environment.


int fesetenv(
   const fenv_t *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.

Return Value

Returns 0 if the environment was successfully set. Otherwise, returns a nonzero value.


The fesetenv function sets the current floating-point environment from the value stored in the fenv_t object pointed to by penv. The floating point environment is the set of status flags and control modes that affect floating-point calculations. This includes the rounding mode and the status flags for floating-point exceptions. If penv is not FE_DFL_ENV or does not point to a valid fenv_t object, subsequent behavior is undefined.

A call to this function sets the exception status flags that are in the penv object, but it does not raise those 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.


Function C header C++ header
fesetenv <fenv.h> <cfenv>

For additional compatibility information, see Compatibility.

See also

Alphabetical Function Reference