int fesetenv (const fenv_t* envp);
Set floating-point environment
Attempts to establish the state of the floating-point environment as represented by the object pointed by envp.

The floating point environment is a set of status flags and control modes affecting floating-point calculations (including both floating-point exceptions and the rounding direction mode).

If successful, the function changes the current state of the floating-point environment without actually raising the exceptions specified in such state.

Programs calling this function shall ensure that pragma FENV_ACCESS is enabled for the call.


Either a pointer to a fenv_t value (filled by a previous call to fegetenv or feholdexcept), or one of the floating-point environment macro values:
FE_DFL_ENVDefault floating-point environment (the same as at program startup).
Certain library implementations may support additional floating-point environment state values (with their corresponding macros also beginning with FE_).

Return Value

Zero, if the state was successfully established.
A non-zero value otherwise.

Data races

Each thread maintains a separate floating-point environment with its own state. Spawning a new thread copies the current state. [This applies to C11 and C++11 implementations]


No-throw guarantee: this function never throws exceptions.

See also