This document discusses dynamic polymorphism in object-oriented programming. It explains that dynamic polymorphism allows an entity to change its behavior depending on circumstances through the use of virtual functions, late binding, and abstract classes. Virtual functions can be overridden in derived classes, and calls to virtual functions are resolved at runtime based on the actual object type. Abstract classes contain pure virtual functions without a body and can only be used as a base class.

1. Dynamic Polymorphism
Objectives
In this lesson, you will learn to:
Implement the concept of binding
Use virtual functions
Use pure virtual functions to create abstract classes
Implement dynamic polymorphism by using late
binding
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2. Dynamic Polymorphism
Dynamic Polymorphism
Refers to any entity changing its form, depending on
circumstances
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3. Dynamic Polymorphism
Binding
Is the process of associating a function with a class by
identifying the type of the object or pointer that is used
to invoke the function
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4. Dynamic Polymorphism
Binding (Contd.)
Example:
calc_net_salary()
Employee class
calc_net_salary() calc_net_salary()
Trainee Class Confirmed Class
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5. Dynamic Polymorphism
Dynamic Binding
Is done during runtime
Is also called late binding
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6. Dynamic Polymorphism
Virtual Function
Is a function that is declared as virtual in a base class
and is redefined by a derived class
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7. Dynamic Polymorphism
Using Virtual Functions
Example:
class Employee
{
.
.
virtual int calc_net_salary();
.
.
};
class Contract:public Employee
{
.
.
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8. Dynamic Polymorphism
Using Virtual Functions (Contd.)
int calc_net_salary();
.
.
.
};
class Direct_Contract: public Contract
{
.
.
int calc_net_salary();
.
.
};
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9. Dynamic Polymorphism
Pure Virtual Function
Is a function without a body
Is created by adding the notation ‘=0’ to the virtual
function declaration
Example:
virtual int calc_net_salary()=0;
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10. Dynamic Polymorphism
Abstract Class
Is a class containing one or more pure virtual
functions
Is used as a base class for deriving specific classes of
the same kind
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11. Dynamic Polymorphism
Static vs Dynamic Polymorphism
Static polymorphism
Is considered more efficient
Is function overloading, which is bound by scopes -
local and class scope
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12. Dynamic Polymorphism
Static vs Dynamic Polymorphism (Contd.)
Dynamic polymorphism
Is considered more flexible
Is based on overriding principles, which, therefore,
is purely class scope and is based on inheritance
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13. Dynamic Polymorphism
Problem Statement 8.D.1
Create an application that:
Accepts customer details
Accepts dealer details
Displays customer details
Displays dealer details
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14. Dynamic Polymorphism
Summary
In this lesson, you learned that:
The instances of an abstract class cannot be created
but pointers to it can be created
A function exhibits dynamic polymorphism when it
exists in more than one form, and calls to its various
forms are resolved dynamically when the program is
executed
Static binding is considered to be more efficient while
dynamic binding is more flexible
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15. Dynamic Polymorphism
Summary (Contd.)
Dynamic polymorphism refers to an entity changing its
form, depending on circumstances
The virtual keyword is used to declare a function as
virtual
Virtual functions that have no body are called pure
virtual functions
A class containing one or more pure virtual functions
is called an abstract class
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