Templates enable us to specify a range of related (overloaded) functions—called function-template specializations (p. 785)—or a range of related classes—called class-template specializations (p. 785).

Class templates provide the means for describing a class generically and for instantiating classes that are type-specific versions of this generic class.

Class templates are called parameterized types (p. 785); they require type parameters to specify how to customize a generic class template to form a specific class-template specialization.

To use class-template specializations you write one class template. When you need a new type-specific class, the compiler writes the source code for the class-template specialization.

A class-template definition (p. 785) looks like a conventional class definition, but it’s preceded by template<typename T> (or template<class T>) to indicate this is a class-template definition. T is a type parameter that acts as a placeholder for the type of the class to create. The type T is mentioned throughout the class definition and member-function definitions as a generic type name.

The names of template parameters must be unique inside a template definition.

Member-function definitions outside a class template each begin with the same template declaration as their class. Then, each function definition resembles a conventional function definition, except that the generic data in the class always is listed generically as type parameter T. The binary scope-resolution operator is used with the class-template name to tie each member-function definition to the class template’s scope.

It’s possible to use nontype parameters (p. 792) in a class or function template declaration.

You can specify a default type argument (p. 792) for a type parameter in the type-parameter list.

A function template may be overloaded in several ways. We can provide other function templates that specify the same function name but different function parameters. A function template can also be overloaded by providing other nontemplate functions with the same function name, but different function parameters. If both the template and non-template versions match a call, the non-template version will be used.