FLT_ROUNDS
Min standard notice:
Header: <cfloat>
Specifies the current rounding direction of floating-point arithmetic operations.
# Declarations
#define FLT_ROUNDS /* implementation defined */
# Notes
The rounding mode can be changed with std::fesetround and FLT_ROUNDS reflects that change.
The possible values of FLT_ROUNDS match the possible values of std::float_round_style, returned by std::numeric_limits::round_style.