Standard library header <cfloat>
From cppreference.com
                    
                                        
                    
                    
                                                            
                    This header was originally in the C standard library as <float.h>.
This header is part of the type support library, in particular it's part of the C numeric limits interface.
[edit] Macros
|    FLT_RADIX  | 
   the radix (integer base) used by the representation of all three floating-point types   (macro constant)  | 
|    DECIMAL_DIG 
(C++11) 
 | 
   number of decimal digits that can be converted to long double and back without losing precision   (macro constant)  | 
|    FLT_MINDBL_MINLDBL_MIN  | 
   minimum value of float, double and long double respectively   (macro constant)  | 
|    FLT_MAXDBL_MAXLDBL_MAX  | 
   maximum value of float, double and long double respectively   (macro constant)  | 
|    FLT_EPSILONDBL_EPSILONLDBL_EPSILON  | 
   difference between 1.0 and the next representable value for float, double and long double respectively   (macro constant)  | 
|    FLT_DIGDBL_DIGLDBL_DIG  | 
   number of decimal digits that can be represented without losing precision for float, double and long double respectively   (macro constant)  | 
|    FLT_MANT_DIGDBL_MANT_DIGLDBL_MANT_DIG  | 
   number of base FLT_RADIX digits that can be represented without losing precision for float, double and long double respectively  (macro constant)  | 
|    FLT_MIN_EXPDBL_MIN_EXPLDBL_MIN_EXP  | 
   minimum negative integer such that FLT_RADIX raised by power one less than that integer is a normalized float, double and long double respectively  (macro constant)  | 
|    FLT_MIN_10_EXPDBL_MIN_10_EXPLDBL_MIN_10_EXP  | 
   minimum negative integer such that 10 raised by power one less than that integer is a normalized float, double and long double respectively   (macro constant)  | 
|    FLT_MAX_EXPDBL_MAX_EXPLDBL_MAX_EXP  | 
   maximum positive integer such that FLT_RADIX raised by power one more than that integer is a normalized float, double and long double respectively  (macro constant)  | 
|    FLT_MAX_10_EXPDBL_MAX_10_EXPLDBL_MAX_10_EXP  | 
   maximum positive integer such that 10 raised by power one more than that integer is a normalized float, double and long double respectively   (macro constant)  | 
|    default rounding mode of floating-point arithmetics   (macro constant)  | 
|
|    (C++11) 
 | 
   specifies in what precision all arithmetic operations are done   (macro constant)  |