Here's a bit of code that might seem like it would work:
#include <cassert>
#include <limits>
enum test { A = 1 };
int main()
{
int max = std::numeric_limits<test>::max();
assert(max > 0);
}
But it fails under both GCC (4.6.2) and clang (2.9) on Linux: max() for enum types is in fact zero! And this remains true even if you use the C++11 enum type specifier to explcitly say what type you want your enum to have.
Why is this? And as for the C++11 behavior, is it something explcitly called for? I could find no mention of it in N2347, the paper on Strongly Typed Enums.
std::numeric_limits
is specialized in the Standard Library "for each arithmetic type, both floating point and integer, includingbool
" (§18.3.2.1/2).Your enumeration
test
is not one of these types, so the primary template is used. Its behavior is specified by §18.3.2.3/1: "The defaultnumeric_limits<T>
template shall have all members, but with0
orfalse
values."If you want to know the traits of the underlying type of
test
, you can useunderlying_type
:Alternatively, you can specialize
numeric_limits
fortest
and have it return the values you want. This is not a particularly good idea, though.