Using numeric_limits::max() in constant expressions
- by FireAphis
Hello,
I would like to define inside a class a constant which value is the maximum possible int. Something like this:
class A
{
...
static const int ERROR_VALUE = std::numeric_limits<int>::max();
...
}
This declaration fails to compile with the following message:
numeric.cpp:8: error: 'std::numeric_limits::max()' cannot appear in a constant-expression
numeric.cpp:8: error: a function call cannot appear in a constant-expression
I understand why this doesn't work, but two things look weird to me:
It seems to me a natural decision to use the value in constant expressions. Why did the language designers decide to make max() a function thus not allowing this usage?
The spec claims in 18.2.1 that
For all members declared static const in the numeric_limits template, specializations shall define these values in such a way that they are usable as integral constant expressions.
Doesn't it mean that I should be able to use it in my scenario and doesn't it contradict the error message?
Thank you.
