Inheritance in C++
Lecture Slides By Adil Aslam
My Email Address:
adilaslam5959@gmail.com
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Object Oriented Programming in C++
Lecture Slides By Adil Aslam
About Me
i am Student of BSCS
My email address:
adilaslam5959@gmail.com

Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Inheritance in C++
Outer Class

Inheritance in C++
• Inherit Definition - Derive quality and
characteristics from parents or ancestors. Like you
inherit features of your parents.
• Example: "She had inherited the beauty of her
mother"
• Inheritance in Object Oriented Programming can be
described as a process of creating new classes from
existing classes.
• The process of obtaining the data members and
methods from one class to another class is known
as inheritance. It is one of the fundamental
features of object-oriented programming.
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Inheritance in C++
• Inheritance is the capability of one class to acquire
properties and characteristics from another class.
The class whose properties are inherited by other
class is called the Parent or Base or Super class.
And, the class which inherits properties of other
class is called Child or Derived or Sub class.
• Inheritance makes the code reusable. When we
inherit an existing class, all its methods and fields
become available in the new class, hence code is
reused.
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
NOTE : All members of a class except Private, are inherited

Advantage of inheritance
• If we develop any application using this concept
than that application have following advantages,
• Application development time is less.
• Application take less memory.
• Application execution time is less.
• Application performance is enhance (improved).
• Redundancy (repetition) of the code is reduced or
minimized so that we get consistence results and
less storage cost.
• Use of Virtual Keyword
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Real life Example of Inheritance
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Diagram
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
In the above diagram data members and methods are represented in broken line
are inherited from faculty class and they are visible in student class logically.

Basic Syntax of Inheritance
• While defining a subclass like this, the super class must be
already defined or at least declared before the subclass
declaration.
• Access Mode is used to specify, the mode in which the
properties of superclass will be inherited into subclass,
public, private or protected.
• : is operator which is used for inheriting the features of base
class into derived class it improves the functionality of
derived class.
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
class Subclass_name : access_mode Superclass_name
{
// data members
// methods
}

Inheritance in C++ Program Example
class Rectangle
{
... .. ...
};
class Area : public Rectangle
{
... .. ...
};
class Perimeter : public Rectangle
{
.... .. ...
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Inheritance in C++ Program Example
class Rectangle
{
... .. ...
};
class Area : public Rectangle
{
... .. ...
};
class Perimeter : public Rectangle
{
.... .. ...
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Super Class/
Parent Class
Sub Class
Perimeter
Sub Class
Area

Inheritance in C++ Program Example
class Rectangle
{
... .. ...
};
class Area : public Rectangle
{
... .. ...
};
class Perimeter : public Rectangle
{
.... .. ...
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Example of Inheritance
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Class Dog inherits
the properties
from its super
class Animal
Animal
Dog

Example of Inheritance
class Animal {
public:
int legs = 4;
};
class Dog : public Animal {
public:
int tail = 1;
};
int main() {
Dog d;
cout <<"Legs are: "<<d.legs<<endl;
cout << "Tail is: "<<d.tail;
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Example of Inheritance
class Animal {
public:
int legs = 4;
};
class Dog : public Animal {
public:
int tail = 1;
};
int main() {
Dog d;
cout <<"Legs are: "<<d.legs<<endl;
cout << "Tail is: "<<d.tail;
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Animal is a
Super Class

Example of Inheritance
class Animal {
public:
int legs = 4;
};
class Dog : public Animal {
public:
int tail = 1;
};
int main() {
Dog d;
cout <<"Legs are: "<<d.legs<<endl;
cout << "Tail is: "<<d.tail;
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Dog is a sub
Class

Example of Inheritance
class Animal {
public:
int legs = 4;
};
class Dog : public Animal {
public:
int tail = 1;
};
int main() {
Dog d;
cout <<"Legs are: "<<d.legs<<endl;
cout << "Tail is: "<<d.tail;
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Sub class Dog inherit
the Properties of
Super class Animal

Example of Inheritance
class Animal {
public:
int legs = 4;
};
class Dog : public Animal {
public:
int tail = 1;
};
int main() {
Dog d;
cout <<"Legs are: "<<d.legs<<endl;
cout << "Tail is: "<<d.tail;
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Create an
object of sub
class

Example of Inheritance
class Animal {
public:
int legs = 4;
};
class Dog : public Animal {
public:
int tail = 1;
};
int main() {
Dog d;
cout <<"Legs are: "<<d.legs<<endl;
cout << "Tail is: "<<d.tail;
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Legs are: 4
Tail is: 1

Inheritance Visibility Mode
• Depending on Access modifier used while
inheritance, the availability of class members of
Super class in the sub class changes. It can either
be private, protected or public.
• 1) Public Inheritance
• This is the most used inheritance mode. In this the
protected member of super class becomes protected
members of sub class and public becomes public.
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
class Subclass : public Superclass

Inheritance Visibility Mode
• 2) Private Inheritance
• In private mode, the protected and public members of
super class become private members of derived class.
• 3) Protected Inheritance
• In protected mode, the public and protected members
of Super class becomes protected members of Sub class.
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
class Subclass : Superclass
// By default its private inheritance
class subclass : protected Superclass

Table showing all the Visibility Modes
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Derived
Class
Derived
Class
Derived
Class
Base class Public Mode Private Mode
Protected
Mode
Private Not Inherited Not Inherited Not Inherited
Protected Protected Private Protected
Public Public Private Protected

Access Control and Inheritance
• A derived class can access all the non-private
members of its base class. Thus base-class
members that should not be accessible to the
member functions of derived classes should be
declared private in the base class.
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Access public protected private
Same class yes yes yes
Derived
classes
yes yes no
Outside
classes
yes no no

Inheritance Visibility Mode
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Member Access Specifier How Members of the Base
Class Appear in the Derived
Class
Private Private members of the base
class are inaccessible to the
derived class.
Protected members of the
base class become private
members of the derived class.
Public members of the base
class become private members
of the derived class.

Inheritance Visibility Mode
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Member Access Specifier How Members of the Base
Class Appear in the Derived
Class
Protected Private members of the base
class are inaccessible to the
derived class.
Protected members of the
base class become protected
members of the derived class.
Public members of the base
class become protected
members of the derived class.

Inheritance Visibility Mode
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Member Access Specifier How Members of the Base
Class Appear in the Derived
Class
Public Private members of the base
class are inaccessible to the
derived class.
Protected members of the
base class become protected
members of the derived class.
Public members of the base
class become public members
of the derived class.

Access Control and Inheritance
• A derived class inherits all base class methods with
the following exceptions:
• Constructors, destructors and copy constructors of the
base class.
• Overloaded operators of the base class.
• The friend functions of the base class.
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

class Base {
public: int m_public; // can be accessed by anybody
private: int m_private; // can only be accessed by Base members and friends (but not derived classes)
protected: int m_protected; // can be accessed by Base members, friends, and derived classes
};
class Derived: public Base {
public: Derived() {
m_public = 1; // allowed: can access public base members from derived class
m_private = 2; // not allowed: can not access private base members from derived class
m_protected = 3; // allowed: can access protected base members from derived class
}
};
int main() {
Base base;
base.m_public = 1; // allowed: can access public members from outside class
base.m_private = 2; // not allowed: can not access private members from outside class
base.m_protected = 3; // not allowed: can not access protected members from outside class
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Types of Inheritance
• Based on number of ways inheriting the feature of
base class into derived class it have five types they
are:
• Single inheritance
• Multiple inheritance
• Hierarchical inheritance
• Multiple inheritance
• Hybrid inheritance
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Types of Inheritance
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Types of Inheritance
• Single Inheritance
• In single inheritance there exists single base class
and single derived class.
• It is the most simplest form of Inheritance.
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Class A
Class B

Single Inheritance
• In single inheritance there exists single base class
and single derived class.
• It is the most simplest form of Inheritance.
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Class A
Class B
Parent Class/
Base Class
Child Class/
Derived Class

Single Inheritance Example
• When a single class is derived from a single parent
class, it is called Single inheritance. It is the
simplest of all inheritance.
• For example,
• Animal is derived from living things
• Car is derived from vehicle
• Typist is derived from staff
• Manager derived from employee
• Circle derived from shapes
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Syntax of Inheritance in C++
cclass base_classname
{
properties...
methods...
};
class derived_classname : visibility_mode base_classname
{
properties...
methods...
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Single Inheritance Example
• For example: Car, Bicycle, Motorcycle are all vehicles and
have many similar properties like tire, brakes, seat, etc. So
they can be derived from class Vehicle.
• Therefore, vehicle is base class and car, bus,
motorcycle are derived classes.
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Vehicle
MotorcycleBusCar

Single Inheritance Example
class A
{
Public:
int salary;
};
class B: public A
{
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Single Inheritance Example
class A
{
Public:
int salary;
};
class B: public A
{
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Class A is a
Parent Class
Class B is a
Child Class

Single Inheritance Example
class A
{
Public:
int salary;
};
class B: public A
{
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Public Data
Member of
Parent Class

Single Inheritance Example
class A
{
Public:
int salary;
};
class B: public A
{
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Child class B inherit
the properties of
Parent class A
After Inheritance Class A
Member Variable goes in Class
B as a Member Variable of
Class B

Example of Single Inheritance-1
class Person
{
public:
string name;
int age;
};
class Student : public Person
{
public:
void show()
{
cout<<"Name is: "<<name<<endl;
cout<<"Age is: "<<age;
}
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Example of Single Inheritance-1
class Person
{
public:
string name;
int age;
};
class Student : public Person
{
public:
void show()
{
cout<<"Name is: "<<name<<endl;
cout<<"Age is: "<<age;
}
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Parent Class
is Person
Child Class
Student Access
the Properties
of the Parent
Class

Example of Single Inheritance-1
class Person
{
public:
string name;
int age;
};
class Student : public Person
{
public:
void show()
{
cout<<"Name is: "<<name<<endl;
cout<<"Age is: "<<age;
}
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
After Inheritance Class Student Look like this
class Student : public Person {
public:
string name;
int age;
public:
void show() {
cout<<"Name is: "<<name<<endl;
cout<<"Age is: "<<age;
}
};

Example of Single Inheritance-2
int main()
{
//Below Creating an object of Child Class(Student)
Student s;
s.name="Adil Aslam";
s.age=20;
//Calling Child Class Function
s.show();
return 0;
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Output of the Previous Program is :
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Another Example of Single Inheritance
class Employee {
public: int salary;
};
class Developer : public Employee {
public:
void data() {
cout<<"Enter the Salary: ";
cin>>salary;
cout<<"Salary is: "<<salary;
}
};
int main() {
Developer obj; //Creating an object of Developer Class (Child Class)
obj.data();
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Another Example of Single Inheritance
class Employee {
public: int salary;
};
class Developer : public Employee {
public:
void data() {
cout<<"Enter the Salary: ";
cin>>salary;
cout<<"Salary is: "<<salary;
}
};
int main() {
Developer obj; //Creating an object of Developer Class (Child Class)
obj.data();
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Parent Class is
Employee
Child Class is
Developer

Output of the Previous Program is :
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Same Previous Program with some Modifications-1
class Employee //Parent Class
{
public:
int salary;
};
class Developer : public Employee //Developer is Child Class
{
public:
void data()
{
cout<<"Enter the Salary: ";
cin>>salary;
cout<<"Salary is: "<<salary<<endl;
}
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Same Previous Program with some Modifications-1
int main()
{
//Creating an object of Developer Class(Child Class)
Developer d;
d.data();
//Creating an object of Employee Class(Parent Class)
Employee e;
e.salary=1000000;
cout<<"Now Salary is: "<<e.salary;
return 0;
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Output of the Previous Program is :
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Ambiguity in Single Inheritance in C++
• If parent and child classes have same named
method, parent name and scope resolution
operator(::) is used. This is done to distinguish the
method of child and parent class since both have
same name.
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
class staff {
public:
void getdata(){}
void display(){}
};
class typist: public staff {
public:
void getdata(){}
void display(){}
};
int main()
{
typist t;
t.display();
}
Above which function is called

Ambiguity in Single Inheritance in C++
• If parent and child classes have same named
method, parent name and scope resolution
operator(::) is used. This is done to distinguish the
method of child and parent class since both have
same name.
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
class staff {
public:
void getdata(){}
void display(){}
};
class typist: public staff {
public:
void getdata(){}
void display(){}
};
int main()
{
typist t;
t.display();
}
Above which function is called
Ans is typist class method is called
Typist Class Method having high
Preference

Ambiguity in Single Inheritance in C++
• If parent and child classes have same named
method, parent name and scope resolution
operator(::) is used. This is done to distinguish the
method of child and parent class since both have
same name.
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
class staff {
public:
void getdata(){}
void display(){}
};
class typist: public staff {
public:
void getdata(){}
void display(){}
};
int main()
{
typist t;
t.display();
}
What about if we want to call
staff Class Method…???

Ambiguity in Single Inheritance in C++
• If parent and child classes have same named
method, parent name and scope resolution
operator(::) is used. This is done to distinguish the
method of child and parent class since both have
same name.
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
class staff {
public:
void getdata(){}
void display(){}
};
class typist: public staff {
public:
void getdata(){}
void display(){}
};
int main()
{
typist t;
t.staff::display();
}
What about if we want to call
staff Class Method…???
Ans is use Scope Resolution
Operator(::)

Example of Single Inheritance-1
class staff {
private:
char name[50];
int code;
public:
void getdata();
void display();
};
class typist: public staff {
private:
int speed;
public:
void getdata();
void display();
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
In this Example we use Scope
Resolution Operator(::)

Example of Single Inheritance-2
void staff::getdata() {
cout<<"Name:";
gets(name);
cout<<"Code:";
cin>>code;
}
void staff::display() {
cout<<"Name:"<<name<<endl;
cout<<"Code:"<<code<<endl;
}
void typist::getdata() {
cout<<"Speed:";
cin>>speed;
}
void typist::display() {
cout<<"Speed:"<<speed<<endl;
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
In this Example we use Scope
Resolution Operator(::)

Example of Single Inheritance-3
int main()
{
typist t;
cout<<"Enter data"<<endl;
t.staff::getdata(); //calling staff class method
t.getdata();
cout<<endl<<"Display data"<<endl;
t.staff::display(); //calling staff class method
t.display();
return 0;
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
In this Example we use Scope
Resolution Operator(::)
In this example, typist class is derived and staff class is
the base class. Public members of class staff such as
staff::getdata() and staff::display() are inherited to class
typist. Since the child is derived from a single parent
class, it is single inheritance.

Output of the Previous Program is :
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

One More Example of Single Inheritance-1
class person { //Parent class
private:
char fname[100],lname[100],gender[10];
protected:
int age;
public:
void input_person();
void display_person();
};
class student: public person { //Child class
private:
char college_name[100];
char level[20];
public:
void input_student();
void display_student();
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

One More Example of Single Inheritance-2
void person::input_person() {
cout<<"First Name: ";
cin>>fname;
cout<<"Last Name: ";
cin>>lname;
cout<<"Gender: ";
cin>>gender;
cout<<"Age: ";
cin>>age;
}
void person::display_person() {
cout<<"First Name : "<<fname<<endl;
cout<<"Last Name : "<<lname<<endl;
cout<<"Gender : "<<gender<<endl;
cout<<"Age : "<<age<<endl;
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

One More Example of Single Inheritance-3
void student::input_student() {
person::input_person();
cout<<"College: ";
fflush(stdin);
gets(college_name);
cout<<"Level: ";
cin>>level; }
void student::display_student() {
person::display_person();
cout<<"College : "<<college_name<<endl;
cout<<"Level : "<<level<<endl; }
int main() {
student s;
cout<<"Input data"<<endl;
s.input_student();
cout<<endl<<"Display data"<<endl;
s.display_student();
return 0;
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Output of the Previous Program is :
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Explanation of Previous Program
• In the previous example, we have a class person with
attributes fname (first name), lname (last name), gender
and age and methods input_person() to input data and
display_person() to display data. Another class student is
derived from person which has college_name and level as
attributes and input_student() and display_student() as
methods to input and display data respectively.
• Here, person is base class and student is derived class.
Since, person has publicly inherited student members, the
private members fname, lname and gender are not
inherited. The protected member age is inherited as a
protected member in student, and public member
functions input_person() and display_person() are
inherited as public members. This is the simplest example of
inheritance.
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Types of Inheritance
• Multiple Inheritance
• In this type of inheritance a single derived class
may inherit from two or more than two base
classes.
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Class A Class B
Class C

Types of Inheritance
• Multiple Inheritance
• In this type of inheritance a single derived class
may inherit from two or more than two base
classes.
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Class A Class B
Class C
Parent ClassParent Class
Child Class

Multiple Inheritance Example
• When a class is derived from two or more base
classes, such inheritance is called Multiple
Inheritance. It allow us to combine the features of
several existing classes into a single class.
• For example,
• Petrol is derived from both liquid and fuel.
• A child has character of both his/her father and
mother, etc.
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Syntax of Multiple Inheritance
class base_class1
{
properties;
methods;
};
class base_class2
{
properties;
methods;
};
class derived_classname : visibility_mode base_class1, visibility_mode base_class2
{
properties;
methods;
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Multiple Inheritance Example
class A
{
};
class B
{
};
class C: public B, public A
{
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Multiple Inheritance Example
class A
{
};
class B
{
};
class C: public B, public A
{
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Parent Class
Parent Class
Child Class
Note: Class A and Class B Both are Parent in Context of Child Class B

Multiple Inheritance Example
class A
{
public: string name;
};
class B
{
public: int marks;
};
class C: public B, public A
{
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Child Class C inherit
the Properties of both
Class A and Class B
After inheritance Child Class C
look Like this
class C: public B, public A
{
public: string name;
public: int marks;
};

Example of Multiple Inheritance
class A {
public: string name;
};
class B {
public: int marks;
};
class C: public B, public A {
public: void show() {
cout<<"Name is: "<<name<<endl;
cout<<"Marks are: "<<marks; }
};
int main() {
C c;
c.name="Adil Aslam";
c.marks=90;
c.show();
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Output of the Previous Program is :
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Ambiguity in Multiple Inheritance
• In multiple inheritance, a single class is derived
from two or more parent classes. So, there may be
a possibility that two or more parents have same
named member function.
• If the object of child class needs to access one of
the same named member function then it results in
ambiguity. The compiler is confused as method of
which class to call on executing the call statement.
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Ambiguity in Multiple Inheritance
class A {
public: void display() {
cout <<"This is method of A";
}
};
class B{
public: void display() {
cout <<"This is method of B";
}
};
class C: public A, public B {
public:
};
int main() {
C sample;
sample.display(); /*causes ambiguity*/
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Ambiguity in Multiple Inheritance
class A {
public: void display() {
cout <<"This is method of A";
}
};
class B{
public: void display() {
cout <<"This is method of B";
}
};
class C: public A, public B {
public:
};
int main() {
C sample;
sample.display(); /*causes ambiguity*/
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Class A and Class B
Both have Member
Function with the same
Name

Ambiguity in Multiple Inheritance
class A {
public: void display() {
cout <<"This is method of A";
}
};
class B{
public: void display() {
cout <<"This is method of B";
}
};
class C: public A, public B {
public:
};
int main() {
C sample;
sample.display(); /*causes ambiguity*/
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Here we call the display
function using object of
class C but compiler
confuse which display
function it call because
Class C inherit the
Properties of both class A
and class B
Class C After Inheritance Look Like this
class C: public A, public B {
public:
void display() {
cout <<"This is method of A";
void display() {
cout <<"This is method of B";
};

Compiler View
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Compiler
Error

Ambiguity Resolution of Multiple Inheritance
• This problem can be resolved by class name and
using scope resolution operator to specify the class
whose method is called.
• In the previous example, if we want to call the method of
class A then we can call it as below,
• Similarly, if we need to call the method of class B then,
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
derived_objectname.parent_classname::same_named_function([parameter]);
sample.A :: display();
sample.B :: display();

Solution of Ambiguity in Multiple Inheritance
class A {
public: void display() {
cout <<"This is method of A";
}
};
class B{
public: void display() {
cout <<"This is method of B";
}
};
class C: public A, public B {
public:
};
int main() {
C sample;
sample.A::display(); //Now Here A Class (Parent Class) Method is Called
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
This is method of A

Solution of Ambiguity in Multiple Inheritance
class A {
public: void display() {
cout <<"This is method of A";
}
};
class B{
public: void display() {
cout <<"This is method of B";
}
};
class C: public A, public B {
public:
};
int main() {
C sample;
sample.B::display(); //Now Here B Class (Parent Class) Method is Called
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
This is method of B

Solution of Ambiguity in Multiple Inheritance-1
class A {
public:
void display()
{
cout <<"This is method of An";
}
};
class B {
public:
void display()
{
cout <<"This is method of B";
}
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Solution of Ambiguity in Multiple Inheritance-2
class C: public A, public B {
public:
void output()
{
A::display();
B::display();
}
};
int main()
{
C sample;
sample.output();
return 0;
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Solution of Ambiguity in Multiple Inheritance-2
class C: public A, public B {
public:
void output()
{
A::display();
B::display();
}
};
int main()
{
C sample;
sample.output();
return 0;
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Here inside a function
body we Set which
function is called

Output of the Previous Program is :
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Another Example of Multiple Inheritance
class Mammal {
public:
Mammal() {
cout << "Mammals can give direct birth." << endl; }
};
class WingedAnimal {
public:
WingedAnimal() {
cout << "Winged animal can flap." << endl; }
};
class Bat: public Mammal, public WingedAnimal {
};
int main() {
Bat b1;
return 0;
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Output of the Previous Program is :
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

One More Example of Multiple Inheritance-1
class student {
protected: int rno,m1,m2;
public:
void get() {
cout<<"Enter the Roll no :";
cin>>rno;
cout<<"Enter the two marks :"<<endl;
cin>>m1>>m2; }
};
class sports {
protected: int sm; // sm = Sports mark
public:
void getsm() {
cout<<"nEnter the sports mark :"<<endl;
cin>>sm; }
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

One More Example of Multiple Inheritance-2
class statement:public student,public sports {
int tot,avg;
public:
void display() {
tot=(m1+m2+sm);
avg=tot/3;
cout<<"nntRoll No : "<<rno<<"ntTotal : "<<tot;
cout<<"ntAverage : "<<avg;
}
};
int main() {
statement obj;
obj.get();
obj.getsm();
obj.display();
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Output of the Previous Program is :
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Example of Multiple Inheritance-1
class liquid {
float specific_gravity;
public: void input() {
cout<<"Specific gravity: ";
cin>>specific_gravity; }
void output() {
cout<<"Specific gravity: "<<specific_gravity<<endl; }
};
class fuel {
float rate;
public: void input() {
cout<<"Rate(per liter): $ ";
cin>>rate; }
void output() {
cout<<"Rate(per liter): $ "<<rate<<endl; }
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Example of Multiple Inheritance-2
class petrol: public liquid, public fuel {
public: void input() {
liquid::input();
fuel::input(); }
void output() {
liquid::output();
fuel::output(); }
};
int main() {
petrol p;
cout<<"Enter data"<<endl;
p.input();
cout<<endl<<"Displaying data"<<endl;
p.output();
return 0;
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Output of the Previous Program is :
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Types of Inheritance
• Hierarchical Inheritance
• In this type of inheritance, multiple derived classes
inherits from a single base class.
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Class A
Class CClass B Class D

Hierarchical Inheritance Example
• When more than one classes are derived from a
single base class, such inheritance is known
as Hierarchical Inheritance, where features that are
common in lower level are included in parent class.
Problems where hierarchy has to be maintained
can be solved easily using this inheritance.
• For Example:
• Civil, Computer, Mechanical, Electrical are derived
from Engineer.
• Natural language, Programming language are
derived from Language.
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Syntax of Hierarchical Inheritance
class base_classname {
properties;
methods;
};
class derived_class1:visibility_mode base_classname {
properties;
methods;
};
class derived_class2:visibility_mode base_classname {
properties;
methods;
};
... ... ...
class derived_classN:visibility_mode base_classname {
properties;
methods;
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Hierarchical Inheritance Example
class A
{
};
class B: public A
{
};
class C: public A
{
};
class D: public A
{
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Hierarchical Inheritance Example
class A
{
};
class B: public A
{
};
class C: public A
{
};
class D: public A
{
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Here A is
Parent Class
Class B, C and D
are Child Classes
of Class A

Example of Hierarchical Inheritance-1
class Side {
protected: int l;
public: void set_values (int x) {
l=x;
}
};
class Square: public Side {
public: int sq() {
return (l *l);
}
};
class Cube:public Side {
public: int cub() {
return (l *l*l);
}
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Example of Hierarchical Inheritance-1
class Side {
protected: int l;
public: void set_values (int x) {
l=x;
}
};
class Square: public Side {
public: int sq() {
return (l *l);
}
};
class Cube:public Side {
public: int cub() {
return (l *l*l);
}
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
Side is a
Parent Class
Class “Square”
is Child of
“Slide” Class
Class “Cube” is
Child of “Slide”
Class

Example of Hierarchical Inheritance-1
class Side {
protected: int l;
public: void set_values (int x) {
l=x;
}
};
class Square: public Side {
public: int sq() {
return (l *l);
}
};
class Cube:public Side {
public: int cub() {
return (l *l*l);
}
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
After Inheritance Class Square
Look Like tis
class Square: public Side {
protected: int l;
public: void set_values (int x)
{
l=x;
}
public: int sq() {
return (l *l);
}
};

Example of Hierarchical Inheritance-1
class Side {
protected: int l;
public: void set_values (int x) {
l=x;
}
};
class Square: public Side {
public: int sq() {
return (l *l);
}
};
class Cube:public Side {
public: int cub() {
return (l *l*l);
}
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
After Inheritance Class Cube
Look Like tis
class Cube: public Side {
protected: int l;
public: void set_values (int x)
{
l=x;
}
public: int cub() {
return (l *l*I);
}
};

Example of Hierarchical Inheritance-2
int main () {
//Creating an Object of Class Square
Square s;
s.set_values (10);
cout<<"---------Result----------"<<endl<<endl;
cout << "The square value is::" << s.sq() << endl;
//Creating an Object of Class Cube
Cube c;
c.set_values (20);
cout << "The cube value is::" << c.cub() << endl;
return 0;
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
In the above example the two derived classes "Square", "Cube"
uses a single base class "Side". Thus two classes are inherited
from a single class. This is the hierarchical inheritance OOP's
concept in C++.

Output of the Previous Program is :
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

One More Example of Hierarchical Inheritance-1
class Shape {
protected: float width, height;
public:
void set_data (float a, float b) {
width = a;
height = b; }
};
class Rectangle: public Shape {
public:
float area () {
return (width * height); }
};
class Triangle: public Shape {
public:
float area () {
return (width * height / 2); }
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

One More Example of Hierarchical Inheritance-1
int main ()
{
//Creating an Object of Class Rectangle
Rectangle rect;
//Creating an Object of Class Triangle
Triangle tri;
rect.set_data (5,3);
tri.set_data (2,5);
cout<<"------------Result------------"<<endl<<endl;
cout <<"Area of Rectangle is: "<<rect.area() << endl;
cout <<"Area of Triangle is: "<<tri.area() << endl;
return 0;
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Explanation of the Previous Program
• The object of the class Rectangle contains :
width, height inherited from Shape becomes the protected
member of Rectangle.
• set_data() inherited from Shape becomes the public
member of Rectangle area is Rectangle’s own public
member
The object of the class Triangle contains :
width, height inherited from Shape becomes the protected
member of Triangle.set_data() inherited from Shape
becomes the public member of Triangle
area is Triangle’s own public member
• set_data () and area() are public members of derived class
and can be accessed from outside class i.e. from main()
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Output of the Previous Program is :
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Example of Hierarchical Inheritance-1
class person {
char name[100],gender[10]; int age;
public:
void getdata() {
cout<<"Name: ";
fflush(stdin); /*clears input stream*/
gets(name);
cout<<"Age: ";
cin>>age;
cout<<"Gender: ";
cin>>gender; }
void display() {
cout<<"Name: "<<name<<endl;
cout<<"Age: "<<age<<endl;
cout<<"Gender: "<<gender<<endl; }
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Example of Hierarchical Inheritance-2
class student: public person{
char institute[100], level[20];
public:
void getdata() {
person::getdata();
cout<<"Name of College/University: ";
fflush(stdin);
gets(institute);
cout<<"Level: ";
cin>>level;
}
void display() {
person::display();
cout<<"Name of College/University: "<<institute<<endl;
cout<<"Level: "<<level<<endl;
}
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Example of Hierarchical Inheritance-3
class employee: public person {
char company[100]; float salary;
public:
void getdata() {
person::getdata();
cout<<"Name of Company: ";
fflush(stdin);
gets(company);
cout<<"Salary: Rs.";
cin>>salary;
}
void display(){
person::display();
cout<<"Name of Company: "<<company<<endl;
cout<<"Salary: Rs."<<salary<<endl;
}
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Example of Hierarchical Inheritance-4
int main()
{
student s;
employee e;
cout<<"Student"<<endl;
cout<<"Enter data"<<endl;
s.getdata();
cout<<endl<<"Displaying data"<<endl;
s.display();
cout<<endl<<"Employee"<<endl;
cout<<"Enter data"<<endl;
e.getdata();
cout<<endl<<"Displaying data"<<endl;
e.display();
return 0;
}
Object Oriented Programming in C++
Lecture Slides By Adil Aslam
In this program student and
employee classes are derived
from person. Person has two
public
methods: getdata() and display().
These methods are inherited by
both student and employee. Input
is given using getdata() method
and displayed
using display() method. This is an
example of hierarchical
inheritance since two classes are
derived from a single class.

Output of the Previous Program is :
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Hierarchical Inheritance Example
class Number
{
private:
int num;
public:
void getNumber() {
cout << "Enter an integer number: ";
cin >> num;
}
int returnNumber() {
return num;
}
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Hierarchical Inheritance Example Cont.
//Base Class 1, to calculate square of a number
class Square : public Number
{
public:
int getSquare() {
int num, sqr;
//get number from class Number
num=returnNumber();
sqr=num*num;
return sqr;
}
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Hierarchical Inheritance Example Cont.
//Base Class 2, to calculate cube of a number
class Cube : public Number
{
private:
public:
int getCube(){
int num, cube;
//get number from class Number
num=returnNumber();
cube=num*num*num;
return cube;
}
};
Object Oriented Programming in C++
Lecture Slides By Adil Aslam

Hierarchical Inheritance Example Cont.
int main() {
Square objS;
Cube objC;
int sqr, cube;
objS.getNumber();
sqr =objS.getSquare();
cout << "Square of "<< objS.returnNumber() << " is: " << sqr << endl;
objC.getNumber();
cube=objC.getCube();
cout << "Cube of "<< objS.returnNumber() << " is: " << cube << endl;
return 0;
}
Object Oriented Programming in C++
Lecture