OBJECT ORIENTED PROGRAMMING AND DATA STRUCTURES. Inheritance

Transcription

1 Inheritance Definition : Inheritance is the process by which objects of one class acquired the properties of objects of another classes. Inheritance is a property by which the new classes are created using the old classes. In other words the new classes can be developed using some of the properties of old classes Base Class : Definition: The old class is referred to as the Base class A class from which other classes are derived. A derived class can inherit members from a base class Syntax: Class Class-name Example: class B int a; void get_a(); M.EZHILVENDAN [AP/IT] [Jawahar Engineering College - Chennai] Page 1

2 Derived Class: Definition: A Class that inherits some or all of its members from another class (Base class) is called as Derived Class Syntax: Class Derived-Class-name : Visibility-Mode Base-Class-Name Example: class D:public B int b; void get_b(); M.EZHILVENDAN [AP/IT] [Jawahar Engineering College - Chennai] Page 2

3 Access Specifier (Visibility Mode) : The access specifier such as Public, Private and Protected determines how elements of base class are inherited by the derived class Base Class Visibility Derived Class Visibility Private Public Protected Private Not Inherited Not Inherited Not Inherited Public Private Public Protected Protected Private Protected Protected Types of Inheritance: 1. Single Inheritance 2. Multiple Inheritance 3. Hierarchical Inheritance 4. Multilevel Inheritance 5. Hybrid Inheritance 1.Single Inheritance: Definition: A Derived Class with only one Base class is called as Single Inheritance. Diagrammatic Representation: Base Class (B) Derived Class (D) Fig: Single Inheritance M.EZHILVENDAN [AP/IT] [Jawahar Engineering College - Chennai] Page 3

4 Syntax: Class Base-Classname Class Derived-Class-name : Visibility-Mode Base-Class-name Example 1: //Single inheritance: public #include<iostream.h> #include<conio.h> class B int a; void get_a(); M.EZHILVENDAN [AP/IT] [Jawahar Engineering College - Chennai] Page 4

5 void B::get_a() cout<<"enter the value of A: "; cin>>a; class D:public B int b; void get_b(); void D::get_b() cout<<"enter the value of B: "; cin>>b; int c; c=a+b; cout<<"the sum of A and B is: "<<c; void main() clrscr(); D d1; d1.get_a(); d1.get_b(); getch(); Output: Enter the value of A: 12 Enter the value of B: 22 The sum of A and B is: 34 M.EZHILVENDAN [AP/IT] [Jawahar Engineering College - Chennai] Page 5

6 Example 2: //Single inheritance: private #include<iostream.h> #include<conio.h> class B int a; void get_a(); void B::get_a() cout<<"enter the value of A: "; cin>>a; class D:private B int b; void get_b(); void D::get_b() get_a( ); cout<<"enter the value of B: "; cin>>b; int c; c=a+b; cout<<"the sum of A and B is: "<<c; M.EZHILVENDAN [AP/IT] [Jawahar Engineering College - Chennai] Page 6

7 void main() clrscr(); D d1; d1.get_b(); getch(); Output: Enter the value of A: 12 Enter the value of B: 22 The sum of A and B is: Multiple Inheritance Definition: A Derived Class derived from several Base class is called as Multiple Inheritance. Diagrammatic Representation: Base Class 1 Base Class 2 Base Class 3 Derived Class Fig: Multiple Inheritance M.EZHILVENDAN [AP/IT] [Jawahar Engineering College - Chennai] Page 7

8 Syntax: Class Derived-Classname : Visibility BaseClass-Name 1, Visibility BaseClass-Name 2 Example: //multiple inheritance #include<iostream.h> #include<conio.h> class M int m; void get_m(int); class N int n; void get_n(int); class P:public M, public N void display(void); M.EZHILVENDAN [AP/IT] [Jawahar Engineering College - Chennai] Page 8

9 void M::get_m(int x) m=x; void N::get_n(int y) n=y; void P::display(void) cout<<"m="<<m<<"\n"; cout<<"n="<<n<<"\n"; cout<<"m*n="<<m*n<<"\n"; void main() clrscr(); P p; p.get_m(10); p.get_n(20); p.display(); getch(); Output: m=10 n=20 m*n= Hierarchical Inheritance: Definition: A Base Class has many Derived Class is called as Hierarchical Inheritance. Diagrammatic Representation: Base Class Derived Class 1 Derived Class 2 Derived Class 3 Fig: Hierarchical Inheritance M.EZHILVENDAN [AP/IT] [Jawahar Engineering College - Chennai] Page 9

10 Syntax: Class Derived-Classname 1 : Visibility-Mode BaseClass-Name Class Derived-Classname 2 : Visibility-Mode BaseClass-Name 4.Multilevel Inheritance: Definition: Mechanism of deriving a class from Another Derived Class is known as Multilevel Inheritance Diagrammatic Representation: Base Class Derived Class 1 Derived Class 2 Fig: Multilevel Inheritance M.EZHILVENDAN [AP/IT] [Jawahar Engineering College - Chennai] Page 10

11 Syntax: Class Base-Classname Class Derived-Classname 1 : Visibility-Mode BaseClass-Name Class Derived-Classname 2 : Visibility-Mode Derived-Classname 1 M.EZHILVENDAN [AP/IT] [Jawahar Engineering College - Chennai] Page 11

12 Example: //Multilevel Inheritance #include<iostream.h> #include<conio.h> class student int roll_number; void get_number(int); void put_number(void); void student::get_number(int a) roll_number=a; void student::put_number() cout<<"roll number:"<<roll_number<<"\n"; class test:public student float sub1; float sub2; void get_marks(float,float); void put_marks(void); void test::get_marks(float x,float y) sub1=x; sub2=y; void test::put_marks() cout<<"\nmarks in sub 1="<<sub1<<"\n"; cout<<"\nmarks in sub 2="<<sub2<<"\n"; M.EZHILVENDAN [AP/IT] [Jawahar Engineering College - Chennai] Page 12

13 class result : public test float total; void display(void); void result::display(void) total=sub1+sub2; put_number(); put_marks(); cout<<"total="<<total<<"\n"; void main() clrscr(); result student1; student1.get_number(111); student1.get_marks(98.0,95.5); student1.display(); getch(); OUTPUT: Roll number:10 Marks in sub 1=98 Marks in sub 2=95.5 Total=193.5 M.EZHILVENDAN [AP/IT] [Jawahar Engineering College - Chennai] Page 13

14 5.Hybrid Inheritance: Definition: Hybrid Inheritance is combination of two or more inheritance Diagrammatic Representation: Base Class Derived Class 1 Derived Class 2 Derived Class 3 Fig : Hybrid Inheritance Syntax: Class Base-Classname 1 M.EZHILVENDAN [AP/IT] [Jawahar Engineering College - Chennai] Page 14

15 Class Derived-Classname 1 : Visibility-Mode BaseClass-Name 1 Class Base-Classname 2 Class Derived-Classname 2 : Visibility Derived-Classname 1, Visibility Base-Classname 2 M.EZHILVENDAN [AP/IT] [Jawahar Engineering College - Chennai] Page 15

16 Example: //Hybrid Inheritance #include<iostream.h> #include<conio.h> class student int roll_number; void get_number(int a) roll_number=a; void put_number(void) cout<<"roll number:"<<roll_number<<"\n"; class test : public student float part1,part2; void get_mark(float x,float y) part1=x; part2=y; void put_marks(void) cout<<"marks obtained:"<<"\n"; cout<<"part1="<<part1<<"\n"; cout<<"part2="<<part2<<"\n"; M.EZHILVENDAN [AP/IT] [Jawahar Engineering College - Chennai] Page 16

17 class sports float score; void get_score(float c) score=c; void put_score(void) cout<<"sport wt:"<<score<<"\n"; class result:public test,public sports float total; void display(void); void result::display(void) total=part1+part2+score; put_number(); put_marks(); put_score(); cout<<"\ntotal score="<<total<<"\n"; void main() clrscr(); result student1; student1.get_number(10); student1.get_mark(27.5,33.0); student1.get_score(6.0); student1.display(); getch(); M.EZHILVENDAN [AP/IT] [Jawahar Engineering College - Chennai] Page 17

18 Output: Roll number:10 Marks obtained: Part 1=27.5 Part 2=33 Sport wt:6 Total score=66.5 M.EZHILVENDAN [AP/IT] [Jawahar Engineering College - Chennai] Page 18