05. inheritance

Rising Technologies, Jalna (MH). + 91 9423156065, http://www.RisingTechnologies.in 1
Haresh Jaiswal
Rising Technologies, Jalna.

Introduction
 Inheritance allows us to extend the definition of a class without
making any physical changes to the existing class.
 Inheritance lets you create new classes reusing some features
from existing class.

Introduction
 Any new class that you create from an existing class is
called derived class & existing class is called as base class.
A
B
Base Class
Derived
Class

Introduction
 The inheritance enables a derived class to inherit features from
its base class. Furthermore, the derived class can add new
features of its own.
A
B
void show()
{
}
void show()
{
}
void print()
{
}

Introduction
 Therefore, rather than to create a completely new class from
scratch, you can take advantage of inheritance and reduce
software complexity.
A
B
void show()
{
}
void show()
{
}
void print()
{
}

Inheritance
Class Bird
Non Flying BirdFlying Bird
Robin Swallow Penguin Kiwi

Inheritance
 The concept of inheritance provides the idea of reusability. This
means that we can add additional features to an existing class
without modifying it.
A
B
void show()
{
}
void show()
{
}
void print()
{
}

Inheritance
 Inheritance is the process by which objects of one class acquire
properties of another class. It supports the concepts of
hierarchical classification.

Forms/Types of Inheritance
 Single Inheritance
 Multiple Inheritance
 Multi-Level Inheritance
 Hierarchical Inheritance
 Hybrid Inheritance

Single Inheritance
 It is the inheritance hierarchy wherein a derived class inherits
from only one base class.
Class A
Class B
Base Class
Derived Class

Multiple Inheritance
 It is the inheritance hierarchy wherein a derived class inherits
from multiple base classes.
Class BClass A
Class C

Multi Level Inheritance
 It is the inheritance hierarchy wherein subclass acts as a base
class for other classes.
Class B
Class A
Class C

Hierarchical Inheritance
 It is the inheritance hierarchy wherein multiple subclasses inherit
from one base class.
Class B
Class A
Class C
Class D Class E
Class D

Hybrid Inheritance
 The inheritance hierarchy that reflects any legal combination of
other four types of inheritance.
Class B
Class A
Class C
Class D

Defining Derived Class
 Derived class can be defined by specifying its relationship with
the base class in addition to its own details.
 In order to derive a class from another, we use a colon (:) in the
declaration of the derived class using the following format.
class Derived_Class : VisiblityModifier Base_Class
{
...
...
};

 Where Derived_Class is the name of the derived class and
Base_Class is the name of the class on which it is based.
{
...
...
};

 The VisiblityModifier is optional, and if present it may be
 public
 protected
 private.
 It describes the access level for the members that are inherited from
the base class.
{
...
...
};

 If VisiblityModifier is not specified then default visibility is
private.
class Derived_Class : Base_Class
{
...
...
};

 A class can have members under following 3 visibilities
 Public
 Protected
 Private
 In inheritance, public & protected members of base class gets
inherited into derived class.
 But private members of base class are inaccessible to derived
class.

Public Derivation
class Abc
{
// members of ABC
};
class Xyz : public Abc
{
// members of XYZ
};

Private Derivation
class Abc
{
// members of ABC
};
class Xyz : private Abc
{
// members of XYZ
};

Protected Derivation
class Abc
{
// members of ABC
};
class Xyz : protected Abc
{
// members of XYZ
};

Default Private Derivation
class Abc
{
// members of ABC
};
class Xyz : Abc
{
// members of XYZ
};

Private Visibility Mode
 When a base class is privately inherited by a derived class,
 All public & protected members of base class becomes private
members of derived class.
 No private member of base class will be accessible by derived class.
 In this case the public as well as protected members of base class
can be accessed by the member functions of derived class.
 But no member of base class can be accessed by object of
derived class.

Public Visibility Mode
 When a base class is publicly inherited by a derived class,
 all public members of base class becomes public members of
derived class.
 all protected members of base class will become protected
 In this case the public members of base class can be accessed via
object of derived class.

Protected Visibility Mode
 C++ Provides a third visibility modifier ‘protected’, which serve a
limited purpose in inheritance.
 A member declared as protected is accessible by the member
functions within its class and any class immediately derived from
it.
 It cannot be accessed by the functions outside these two classes.

Protected Visibility Mode
 When a base class is protectedly inherited by a derived class,
 all public & protected members of base class becomes protected
 In this case no members of base class can be accessed via object
of derived class.

Visibility Modes
class ABC
{
private: //optional
//accessible to member functions within this class only.
protected:
//accessible to member functions within this class and
derived class only.
public:
//accessible to all functions within the program.
};

Private
Protected
Public
Private
Protected
Public
Private
Protected
Public
Private
Protected
Public
Not InheritableNot Inheritable
Class B : Public A
Class A
Class C : Private A
Class X : Protected B

05. inheritance

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