如何在模板中为类型引入名称别名

Question

template<typename T>
using Value_type<T> = typename T::value_type;

I get errors:

expected '=' before '<' token

expected type-specifier before '<' token

Answer 1

Like this:

template <typename T>
using Value_type = typename T::value_type;

Just like in the declaration of any primary template, the name of the template itself is not punctuated with the template parameter list.

Answer 2

template<typename T>
using Value_type = typename T::value_type;