Class template

Class template in c++

1. Class Template

2. Class Template 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. Inheritance of Class Template 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 