Introduction to Inheritance

P R E P A R E D B Y :
S H R E Y A S S
K E S H A V V
U N D E R T H E G U I D A N C E O F :
M R S . A R C H A N A S A I D
S E C O M P , A I S S M S ’ I O I T , P U N E
INHERITANCE

BASICS
 Object Oriented Programming has different unique
and important features like classes, objects,
inheritance and polymorphism.
 Inheritance is the concept using which one class
can derive the properties of another class.
 This provides reusability in the program code.
 Due to this, cost of program development is
reduced.

EXAMPLE
 Car is a classification of Four Wheeler. Here Car acquires
the properties of a four-wheeler. Other classifications could
be a jeep, tempo, van etc. Four Wheeler defines a class of
vehicles that have four wheels, and specific range of engine
power, load carrying capacity etc. Car (termed as a sub-
class) acquires these properties from Four Wheeler (termed
as a super-class), and has some specific properties, which
are different from other classifications of Four Wheeler,
such as luxury, comfort, shape, size, usage etc.
 A car can have further classification such as an open car,
small car, big car etc, which will acquire the properties from
both Four Wheeler and Car, but will still have some specific
properties. This way the level of hierarchy can be extended
to any level.

BASE CLASS AND DERIVED CLASS
 Base class is the class whose properties are
inherited by another class.
 Derived class is the class which inherits the
properties of another class.
 Base class is also known as parent class or old
class.
 Derived class is also known as child class or new
class.
 A derived class inherit the properties of base class
and can have its own extra properties as well.

ACCESS SPECIFIERS
 Access specifiers specify the scope of the data declared in them, i.e. they
tell us in which all parts of the program can those data members or
member functions be accessed.
 C++ has provided us with 3 access specifiers, namely private, protected
and public.
 Members declared as private in a class can only be accessed by the
methods of the same class which are declared in public section.
 Members declared as protected are the same as private members. The
only difference is that protected members can be inherited in adjacent
derived classes whereas private members are not inherited at all.
 Members declared as public can be accessed anywhere in the program.

MODES OF INHERITANCE
 A class(derived class) can derive the properties of another class(base
class) in 3 modes: private, protected and public.
 If the derived class inherits in private mode, both the protected as well
as the public members of the base class become the private members of
the derived class.
 If the derived class inherits in protected mode, both the protected and
the public members of the base class become the protected members of
the derived class.
 If the derived class inherits in public mode, then the protected
members of the base class will become the protected members of the
derived class, whereas the public members of the base class will
become the public members of the derived class.
 Private members of the base class will not get inherited at any cost.

TYPES OF INHERITANCE
 There are 5 types of inheritance:
 1. Single Inheritance
 2. Multiple Inheritance
 3. Multilevel Inheritance
 4. Hierarchical Inheritance
 5. Hybrid Inheritance

SINGLE INHERITANCE
 In this type of inheritance, a single derived class
inherits the properties of a single base class.
 In the above example, B is the derived class
inheriting the properties of base class A.
A
B

MULTIPLE INHERITANCE
 In this type of inheritance, a single derived class
inherits the properties of more than one base classes.
 In the above example, C is a derived class inheriting
from two base classes, A and B.
A B
C

MULTILEVEL INHERITANCE
 In this type of inheritance, a derived class acts as a
base class to another class.
 In the above example, B is a derived class inheriting from
base class A, but B also acts as a base class to class C.
A
B
C

HIERARCHICAL INHERITANCE
 In this type of inheritance, more than one derived
classes inherit the properties of a single base class.
 In the above example, B and C are two different
derived classes inheriting from a single base class A.
A
B C

HYBRID INHERITANCE
 It is a mixture of two or more types of inheritance.
 In the above example, classes B and C inherit from base
class A(hierarchical inheritance) and further, class D
inherits from classes B and C(multiple inheritance). So, it
becomes hybrid inheritance.
A
D
B C

ORDER OF CALLING CONSTRUCTORS AND
DESTRUCTORS
 Order of calling constructors and destructors in
inheritance is as follows:
 First, constructor of base class is invoked.
 Then, constructor of derived class is invoked.
 After that, destructor of derived class is invoked.
 At last, destructor of base class is invoked.

Introduction to Inheritance

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Introduction to Inheritance