std::fegetround,std::fesetround (3) - Linux Manuals
Defined in header <cfenv>
int fesetround( int round ) (1) (since C++11)
int fegetround() (2) (since C++11)
Manages the floating-point rounding direction.
1) Attempts to establish the floating-point rounding direction equal to the argument round, which is expected to be one of the floating_point_rounding_macros.
2) Returns the value of the floating_point_rounding_macro that corresponds to the current rounding direction.
round - rounding direction, one of floating_point_rounding_macros
1) 0 on success, non-zero otherwise.
2) the floating_point_rounding_macro describing the current rounding direction or a negative value if the direction cannot be determined
The current rounding mode, reflecting the effects of the most recent fesetround, can also be queried with FLT_ROUNDS
See floating-point_rounding_macros for the effects of rounding.
// Run this code
nearbyintl nearest integer using current rounding mode
llrintf nearest integer using current rounding mode with
llrintl exception if the result differs