Polymorphism in C++

POLYMORPHISM
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Presented by: The Camouflage
Gagan Puri
Bikram Bhurtel
Rabin BK
BSc.CSIT 3rd Semester

Introduction
Static polymorphism
Overloading
Overriding
Dynamic polymorphism
Virtual function and binding
References
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Derived form the Greek word polymorphous
Real life example:- a man at a same time is a father, a husband, a
employee
In C++ how polymorphism can be achieved
Introduction
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Same function name is given to different function
Differ point:
The number of parameters
The data type of parameters
The order of appearance
Function Overloading
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If derived class defines same function as defined in its base class, it
is known as function overriding in C++
used as static as well as dynamic polymorphism
Uses same method name and same type signature
 Used by a child class to change behavior it inherited from its parent
Function Overriding
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Presence of Inheritence
Must have exactly the same declaration in both base and
derived class
Requirement for Overriding
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Accessing Overridden Functions
10

• A type of dynamic polymorphism
• Uses pointer
• Compiler performs late binding/run time binding/dynamic
binding on this function
• Compiler gives preference to address in pointer
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Virtual function
int main(){
Animal *a;
Cat c;
a = &c;
a -> sound();
return 0;
}
class Animal{
public:
virtual void sound(){
cout<<"Base sound"<<endl;
}
};
class Cat:public Animal{
public:
void sound(){
cout<<"Meow"<<endl;
}
};

• A class with pure virtual function is called an abstract class
• We cannot create an object of abstract class
• If a virtual function is equal to 0, it is a pure virtual function
• virtual void sound()=0; //pure virtual function
• It has no definition and also called as do nothing function
• Once made it must be used in derived classes (compulsory else error is
thrown)
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Pure Virtual function
class Animal{
public:
virtual void sound()=0;
};
class Cat{
public:
void sound(){
cout<<"Meow"<<endl;
}
};
class Dog{
public:
void sound(){
cout<<"Woff"<<endl;
}
};
int main(){
Cat c;
Dog d;
c.sound();
d.sound();
return 0;
}
Object of class
Animal is not
created

• Similar to abstract class
• Object of this class cannot be created
• All of its function are virtual and does not have member variables
• Derived class must implement all the functions i.e., provide definition
• We may or may not inherit the base class
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Interface class
class Animal{
public:
virtual void sound()=0;
virtual void food()=0;
};
class Cat{
public:
void sound(){
cout<<"Meow"<<endl;
}
void food(){
cout<<"Milk"<<endl;
}
};
class Dog{
public:
void sound(){
cout<<"Woff"<<endl;
}
void food(){
cout<<"Meat"<<endl;
}
};
int main(){
Cat c;
Dog d;
c.sound();
c.food();
d.sound();
d.food();
return 0;
}
Object of
interface class
Animal is not
created
Inheritance of
the base class
is not
necessary

References
• https://www.codesdope.com/cpp-virtual-and-abstract/
• https://www.youtube.com/watch?v=SvesRBYu65k
• https://www.youtube.com/watch?v=SF8HbxDbNr0&t=309s
• https://www.studytonight.com/cpp/function-overriding.php
• https://www.programiz.com/cpp-programming/function-overriding
• https://www.careercup.com/question?id=1874672
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Polymorphism in C++

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