FLT_ROUNDS

From cppreference.com

Defined in header `<cfloat>`
#define FLT_ROUNDS /* implementation defined */

Specifies the current rounding direction of floating-point arithmetic operations.

Value	Explanation
`-1`	the default rounding direction is not known
`0`	toward zero; same meaning as FE_TOWARDZERO
`1`	to nearest; same meaning as FE_TONEAREST
`2`	towards positive infinity; same meaning as FE_UPWARD
`3`	towards negative infinity; same meaning as FE_DOWNWARD
other values	implementation-defined behavior

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 .

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float_round_style	indicates floating-point rounding modes (enum)
fegetround fesetround (C++11) (C++11)	gets or sets rounding direction (function)
FE_DOWNWARD FE_TONEAREST FE_TOWARDZERO FE_UPWARD (C++11)	floating-point rounding direction (macro constant)
C documentation for FLT_ROUNDS