c++: Does gcc provide extended macro/function like “countof” the size of an array?

问题

VC provides a macro called "_countof" inside "stdlib.h", will calculates in compile time, the number of an array's elements.

My question is does gcc provide a similar utility? Thanks.

回答1:

In C++17, the std::size function template will return the size of an array or container.

A possible implementation is given, so you can write your own until C++17 becomes available:

template <class T, std::size_t N>
constexpr std::size_t size(const T (&array)[N]) noexcept
{
    return N;
}

This will work on any conforming C++11 compiler, so it is a lot more portable than compiler-specific extensions.

来源：https://stackoverflow.com/questions/43444235/c-does-gcc-provide-extended-macro-function-like-countof-the-size-of-an-arra