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_RADIX digits 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_RADIX raised 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_RADIX raised 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)
specifies in what precision all arithmetic operations are done
(macro constant)