13. Study Guide

C++ templates and Java generic classes are nearly identical in syntax and usage. However, C++ templates are more extensive or powerful than Java generics in two ways:

Much like function arguments generalize data, templates generalize data types. "Regular" function arguments act as placeholders for data passed into the function when the program calls it at runtime. Template variables are also placeholders, but the program replaces them with data type names. All valid data types, including all fundamental types like char, int, and double, and structure and class names, can replace a template variable. However, the replacement can't occur before the user specifies the replacement type. To satisfy this requirement, programmers place templates in header files where the compiler processes them after the user-specified types replace the template variables.

Know

C++ programmers may choose one of two keywords: class or typename
Traditionally, programmers use T as the template variable when the template only has one
Programmers use more descriptive template variables names when writing templates that have two or more template variables

The syntax for using templates with a standalone (non-member) function

template <class T>
int min(T v1, T v2)
{
	...
}

template <typename T>
int min(T v1, T v2)
{
	...
}

The syntax for using templates with a class and its member functions

template <class T>
class stack
{
	private:
		T	st[100];
	public:
		void	push(T data);
};

template <typename T>
class stack
{
	private:
		T	st[100];
	public:
		void	push(T data);
};

template <class T>
void stack<T>::push(T data)
{
	...
}

template <typename T>
void stack<T>::push(T data)
{
	...
}

The syntax for instantiating an object from a template class while specifying the template type (Employee is the name of a class)
Stack<int> stack1;
Stack<Employee> stack2;