The numeric_limits class template provides a C++ program with information about various properties of the implementation's representation of the arithmetic types.
Specializations shall be provided for each arithmetic type, both floating point and integer, including bool. The member is_specialized shall be true for all such specializations of numeric_limits.
For all members declared static constexpr in the numeric_limits template, specializations shall define these values in such a way that they are usable as constant expressions.