Declaring a Class Template’s Member Functions Outside the Class Template Definition

Though we did not do so in our Stack class template, member-function definitions can appear outside a class template definition. If you do this, each must begin with the template keyword followed by the same set of template parameters as the class template. In addition, the member functions must be qualified with the class name and scope resolution operator. For example, you can define the pop function outside the class-template definition as follows:

Stack<T>:: indicates that pop is in the scope of class Stack<T>. The Standard Library’s container classes tend to define all their member functions inside their class definitions.