Understanding variadic templates

In the previous section, we learned how to write function or class templates with a fixed number of type parameters. But since C++11, standard generic functions and class templates can accept a variable number of type parameters. This is called variadic templates, which is an extension of C++ in Further reading context [6]. We will learn about the syntax and usage of variadic templates by looking at examples.

Syntax

If a function or class template takes zero or more parameters, it can be defined as follows:

//a class template with zero or more type parameters
template <typename... Args> class X { ... };     

//a function template with zero or more type parameters
template <typename.....