Class templates allow the creation of common classes that can operate on different data types. A class template is defined with generic data types that are replaced when an object is created. The syntax uses angle brackets <> to declare the template type(s) T. Objects are created by specifying the type, like Stack<double>. Template functions are declared normally but preceded with the template type(s). Class templates can also take non-type parameters with default arguments. Derived classes can be created from template base classes while restricting the template feature. Specialization allows overriding the generated code for specific types.

2. A class template is a common class that
represent various similar classes operating
on data of different types.
Once a class template is defined, we can
create an object of that class using a
specific basic or user defined data types to
replace the generic data types used during
class definition

3. Syntax of Class Template
Template<class T1,class T2,…>
Class classname
{
attributes;
methods;
};
T is the variable of template type.
<>(angle bracket) is used to declare
variables of template type, one or more
variables are declared separated by comma

4. To create an object of the class, type
ClassName< type > myObject;
Example: Stack< double >
doubleStack;
Template class functions
Declared normally, but preceded by
template<class T>
Generic data in class listed as type T
Binary scope resolution operator used

5. Template class function definition:
template<class T>
MyClass< T >::MyClass(int size)
{
myArray = new T[size];
}
Constructor definition - creates an array of
type T

6. Class Templates and Non-type Parameters
Can use non-type parameters in templates
Default argument
Treated as const
Example:
Template <class T, int elements>
Stack<double, 100>
mostRecentSalesFigures;
Declares object of type
Stack<double,100>

7. This may appear in the class definition:
T stackHolder[ elements ];
Creates array at compile time, rather than
dynamic allocation at execution time
 Classes can be overridden
For template class Array, define a class
named
Array<myCreatedType>
This new class overrides then class template
for myCreatedType
The template remains for unoverriden types

8. Class templates and static variables :
The rule for class templates is same as
function templates.
Each instantiation of class template has its
own copy of member static variables.
A class generated from a class template is
called a generated class.

9. Derive a class template from a base class,
which is a template class.
Derive a class template from a base class,
which is a template class, add more
template members in the derived class.
Derive a class from a base class which is
not a template, and template member to
that class.

10. Derive a class from a base class which is a
template class and restrict the template
feature, so that the derived class and its
derivatives do not have the template feature.
The syntax for declaring derived classes from
templatebased
base classes is as :
template <class T1, …..>
class baseclass
{
// template type data and functions
};

11. template <class T1, …..>
class derivedclass : public baseclass <T1,
….>
{
// template type data and functions
};
Class Template Specialization :
In some cases it is possible to override the
template-generated code by providing special
definitions for specific types. This called
template specialization.

12.  Thank You 