Defined in header <cfloat>  

#define FLT_ROUNDS /* implementation defined */ 
Specifies the current rounding direction of floatingpoint 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  implementationdefined 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
.
indicates floatingpoint rounding modes (enum) 

(C++11)(C++11)  gets or sets rounding direction (function) 
(C++11)  floatingpoint rounding direction (macro constant) 
C documentation for FLT_ROUNDS 
© cppreference.com
Licensed under the Creative Commons AttributionShareAlike Unported License v3.0.
https://en.cppreference.com/w/cpp/types/climits/FLT_ROUNDS