c++ - Why can't I pass a type member of a class as a template parameter? -

i unable pass type member of class template parameter. example in following piece of code :

std::array<int, 1> a; std::array<typename a::value_type, 1> a2; 

won't compile.

what reason ? there workaround?

a not type, hence can't apply :: it. can use decltype retrieve a's type :

std::array<int, 1> a; std::array<decltype(a)::value_type, 1> a2;