Using numeric_limits::max() in constant expressions
Looks like a bit of a defect...
In C++0x, numeric_limits
will have everything marked with constexpr
, meaning you will be able to use min()
and max()
as compile-time constants.
While the current standard lacks support here, for integral types Boost.IntegerTraits gives you the compile time constants const_min
and const_max
.
The problem arises from §9.4.2/4:
If a static data member is of const integral or const enumeration type, its declaration in the class definition can specify a constant-initializer which shall be an integral constant expression (5.19). In that case, the member can appear in integral constant expressions.
Note that it adds:
The member shall still be defined in a name- space scope if it is used in the program and the namespace scope definition shall not contain an initializer.
As others already mentioned numeric_limit
s min()
and max()
simply aren't integral constant expressions, i.e. compile time constants.
You want:
#include <limits>
struct A {
static const int ERROR_VALUE;
};
const int A::ERROR_VALUE = std::numeric_limits<int>::max();
Put the class/struct in a header and the definition in a .cpp file.