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_MIN DBL_MIN LDBL_MIN | minimum value of float, double and long double respectively (macro constant) | 
| FLT_MAX DBL_MAX LDBL_MAX | maximum value of float, double and long double respectively (macro constant) | 
| FLT_EPSILON DBL_EPSILON LDBL_EPSILON | difference between 1.0 and the next representable value for float, double and long double respectively (macro constant) | 
| FLT_DIG DBL_DIG LDBL_DIG | number of decimal digits that can be represented without losing precision for float, double and long double respectively (macro constant) | 
| FLT_MANT_DIG DBL_MANT_DIG LDBL_MANT_DIG | number of base FLT_RADIXdigits that can be represented without losing precision for float, double and long double respectively(macro constant) | 
| FLT_MIN_EXP DBL_MIN_EXP LDBL_MIN_EXP | minimum negative integer such that FLT_RADIXraised by power one less than that integer is a normalized float, double and long double respectively(macro constant) | 
| FLT_MIN_10_EXP DBL_MIN_10_EXP LDBL_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_EXP DBL_MAX_EXP LDBL_MAX_EXP | maximum positive integer such that FLT_RADIXraised by power one more than that integer is a normalized float, double and long double respectively(macro constant) | 
| FLT_MAX_10_EXP DBL_MAX_10_EXP LDBL_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) | 


