10.Inheritance.ppt for oops programinggg

10-2
What is Inheritance?
Generalization vs. Specialization
• Real-life objects are typically specialized versions of
other more general objects.
• The term “insect” describes a very general type of
creature with numerous characteristics.
• Grasshoppers and bumblebees are insects
– They share the general characteristics of an insect.
– However, they have special characteristics of their own.
• grasshoppers have a jumping ability, and
• bumblebees have a stinger.
• Grasshoppers and bumblebees are specialized
versions of an insect.

10-4
The “is a” Relationship
• The relationship between a superclass and an inherited
class is called an “is a” relationship.
– A grasshopper “is a” insect.
– A poodle “is a” dog.
– A car “is a” vehicle.
• A specialized object has:
– all of the characteristics of the general object, plus
– additional characteristics that make it special.
• In object-oriented programming, inheritance is used to
create an “is a” relationship among classes.

10-5
The “is a” Relationship
• We can extend the capabilities of a class.
• Inheritance involves a superclass and a subclass.
– The superclass is the general class and
– the subclass is the specialized class.
• The subclass is based on, or extended from, the superclass.
– Superclasses are also called base classes, and
– subclasses are also called derived classes.
• The relationship of classes can be thought of as parent
classes and child classes.

10-6
Inheritance, Fields and Methods
• Members of the superclass that are marked private:
– are not inherited by the subclass,
– exist in memory when the object of the subclass is created
– may only be accessed from the subclass by public methods
of the superclass.
• Members of the superclass that are marked public:
– are inherited by the subclass, and
– may be directly accessed from the subclass.

Inheritance
• It is the Process of creating a New class from an existing class.
• The Existing class is called Base or Parent class.
• The New class is called as Child or Derived Class
base
subclass1 subclass2

Derived class
Base Class
Methods
and
Properties
Base class methods
+
Additional methods
Inheritance is the property that allows the
reuse of an existing class to build a new class

Advantages
 It permits code reusability. So, save time and
increase the program reliability.
 Improve Program Reliability
 It Permits code sharing

Syntax for Inheritance
class <derived classname > : visibility mode <base classname >
{
---
----
};

visibility mode
• The visibility mode specifies whether the features are
privately derived or publicly derived.
• The default visibility mode is private.
• Privately Inherited: public members of the base class
become private members of the derived class, can be
accessed only by the member functions of the derived
class.
• Publicly inherited: public members of the base class
become public members of the derived class and can be
accessed by the derived class objects.
• Private members of the base class are not inherited in
both the cases.

Inheritance
Multilevel
Inheritance
Single Inheritance
Multiple Inheritance
Hierarchical
Inheritance

Single Inheritance
A class can be derived from a single base class is called single
inheritance
Person
Employee

• #include <iostream>
• using namespace std;
• // Base class
• class Shape {
• public:
• void setWidth(int w) {
• width = w;
• }
• void setHeight(int h) {
• height = h;
• }
• protected:
• int width;
• int height;
• };
• // Derived class
• class Rectangle : public
Shape {
• public:
• int getArea() {
• return (width *
height);
• }
• };

• int main(void) {
• Rectangle Rect;
• Rect.setWidth(5);
• Rect.setHeight(7);
• // Print the area of the object.
• cout << "Total area: " << Rect.getArea() <<
endl;
• return 0;
• }

Visibility of inherited members

Access control to the members of a
class

Multilevel
Inheritance
Vehicle
Car
Racing car
Person
Employee
Part time
Employee
A class be can derived from a derived class which is known as multilevel
inheritance.

It is the process of creating new class from more than one base
classes.
Syntax :
class <derived class >:<access specifier>
base_class1,<access specifier> base_class2...
{
private :
// members;
protected :
// members;
public :
//memebers;
};
Multiple Inheritance
Person Employee
Teacher

Same Data Member Name in
Base and Derived Class
Single level inheretance

• class ClassA
• {
• protected :
• int width, height;
• public :
• void set_values(int x, int y)
• {
• width = x;
• height = y;
• }
• };
• class ClassC:public ClassA
• {
• protected:
•
• public :
• int area()
• {
• return (width *height);
• }
• };

Same Data Member Name in Base
and Derived Class
• int main()
• {
• ClassC Obj;
• Obj.set_values(10, 20);
• cout << Obj.area() <<
endl;
• return 0;
• }
• Output: 0

• class ClassA
• {
• protected :
• public :
• void set_values(int x, int y)
• {
• width = x;
• height = y;
• }
• };
• class ClassC:public ClassA
• {
• protected:
•
• public :
• int area()
• {
• return (ClassA::width
*ClassA::height);
• }
• };

and Derived Class
• int main()
• {
• ClassC Obj;
• Obj.set_values(10, 20);
• cout << Obj.area() <<
endl;
• return 0;
• }
• Output: 200

Same Data Member Name in
Base and Derived Class
Multiple inheretance

• class person
• {
• protected:
• int regno;
• string name;
• };
• class student
• {
• protected:
• string name;
• int regno;
• };
• class studentgrade:public
person,public student
• {
• private:
• string grade;
• public:
• void details()
• {
• cin>>name;
• cin>>regno;
• }
• void display()
• {
• cout<<name;
• cout<<regno;
• }
• };

and Derived Class
• int main()
• {
• studentgrade a;
•
• a.details();
• a.display();
• }
• error: reference to
'name' is ambiguous
25 | cin>>name;
|
^~~~/tmp/TQ6cOvUM4
U.cpp:13:15: note:
candidates are:
'std::string
student::name' 13 |
string name;

• class person
• {
• protected:
• int regno;
• string name;
• };
• class student
• {
• protected:
• string name;
• int regno;
• };
• class studentgrade:public
person,public student
• {
• private:
• string grade;
• public:
• void details()
• {
• cin>>person::name;
• cin>>person::regno;
• }
• void display()
• {
• cout<<person::name;
• cout<<person::regno;

and Derived Class
• int main()
• {
• studentgrade a;
•
• a.details();
• a.display();
• }
• saira
• 23
• saira23

Hierarchical Inheritance
Employee
Permanent
Employee
Temporary
Employee
If more than one class is inherited from a base class, it's known as hierarchical
inheritance. In general, all features that are common in child classes are included
in base class in hierarchical inheritance.
Employee: Data members: id and name
Permanent Employee: designation and department, getdetails()
and displaydetails()
Temporary employee: no.of working day and contrctor name,
getdetails and displaydetails

Hybrid Inheritance
The process of combining more than one type
of Inheritance together while deriving
subclasses in a program is called a Hybrid
Inheritance.

Person: name and age[protected], get() and print()
Student: rollno and marks[private], get() and print()
Gate Score: gatescore[private], get() and print()
PG-Student :dept_name[private]. get() and print()

10.Inheritance.ppt for oops programinggg

10.Inheritance.ppt for oops programinggg

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