Lec5.ppt
- 2. Lesson Objectives Definition of Inheritance Hierarchy of Inheritance Type of Inheritance C++ Inheritance Implementation
- 3. Introduction Inheritance denotes an is-a relationship. The natural phenomenon where one concept can be viewed as a sub-concept of another Mammal Human More General class More Specific class is-a
- 4. Inheritance What do the sub-class inherit from the Main class? All Features! Can there be sub-class have feature not in the main class? Yes! Human inherits all features in the mammal class in addition to his own features! Mammal Mammal Glands Vertebral Column Human Mammalian glans Vertebral column is-a
- 5. Examples of Inheritance A car is a vehicle. Earth is a planet Orange is a fruit. A surgeon is a doctor. A dog is an animal.
- 6. Hierarchy of Inheritances Mammal Mammal Glands Vertebral Column Human Vertical orientation Dog Non Vertical orientation Homo Sapien Homo Erectus Dalmatian Doodle
- 7. Inheritance: Adopted in OOP The process of creating new classes, from existing ones. The existing class is called base/Super classes The new class is called derived/Sub classes A Derived class has the potential to inherit all the capabilities of the base class in addition to its own.
- 8. Inheritance - Illustration A Derived class has the potential to inherit all the capabilities of the base class in addition to its own. Base Class Feature A Feature B Subclass Feature A Feature B Feature C Inherits From
- 9. Advantages of Inheritance Permits code reusability Once a class has been written to perform a given function, it can always be adapted to perform other functions through inheritance instead of modifying its code. Reusing existing code saves time and money and increases a program’s reliability. Reusability ensures the ease of distributing class libraries.
- 10. Specifying the Derived Class Inheritance is specified using the colon (:) as follows: class Subclass: Baseclass If Baseclass has already been declared and accessible
- 11. Type of Inheritance (Access ) When deriving a class from a base class, the base class may be inherited through public, protected or private inheritance. The type of inheritance is specified by the access- specifier. We hardly use protected or private inheritance, but public inheritance is commonly used. While using different type of inheritance, following rules are applied:
- 12. Type of Inheritance Public Inheritance: When deriving a class from a public base class, public members of the base class become public members of the derived class and protected members of the base class become protected members of the derived class. A base class's private members are never accessible directly from a derived class, but can be accessed through calls to the public and protected members of the base class.
- 13. Type of Inheritance Protected Inheritance: When deriving from a protected base class, public and protected members of the base class become protected members of the derived class. Private Inheritance: When deriving from a private base class, public and protected members of the base class become private members of the derived class
- 14. C++ Inheritance General Format for implementing the concept of Inheritance: class derived_classname: access specifier baseclassname For example, if the base class is MyClass and the derived class is sample it is specified as: class sample: public MyClass The above makes sample have access to both public and protected variables of base class MyClass
- 15. C++ Inheritance Inheritance Example: class MyClass { public: MyClass(void) { x=0; } void f(int n1) { x= n1*5;} void output(void) { cout<<x; } private: int x; };
- 16. C++ Inheritance Inheritance Example: class sample: public MyClass { public: sample(void) { s1=0; } void f1(int n1) { s1=n1*10;} void output(void) { MyClass::output(); cout << s1; } private: int s1;
- 17. C++ Inheritance Inheritance Example: int main(void) { sample s; s.f(10); s.output(); s.f1(20); s.output(); } The output of the above program is 50 200
- 18. Types of Inheritance (Hierarchy) 1. Single class Inheritance: Single inheritance is the one where you have a single base class and a single derived class. Class Employee Class Manager It is a Base class (super) it is a sub class (derived)
- 19. Types of Inheritance (Hierarchy) 2. Multilevel Inheritance: In Multi level inheritance, a class inherits its properties from another derived class. Class A Class B it is a Base class (super) of B it is a sub class (derived) of A and base class of class C Class C derived class(sub) of class B
- 20. Types of Inheritance (Hierarchy) 3. Multiple Inheritances: In Multiple inheritances, a derived class inherits from multiple base classes. It has properties of both the base classes. Class A Class B Base class Class C Derived class
- 21. Types of Inheritance 5. Hybrid Inheritance: Class A Class B Class D Class C
- 22. Summary Definition of Inheritance Hierarchy of Inheritance Type of Inheritance C++ Inheritance Implementation
- 23. Question Time
- 25. Brain Teaser • After her death, a mother left her sons her entire £5000 fortune. • The eldest son received £3000. • The rest was shared equally between whomever remained. • How much did they each get?
- 26. Brain Teaser • A man left an inheritance of $10,000 to three relatives and their wives. Together the wives received $3960. Janine received $100 more than Cathy, and Maria received $100 more than Janine. Joe received the same amount as his wife, Hary got half as much again as his wife, and Tom received twice as much as his wife. • How much did each receive?
Editor's Notes
- #7: If more than one class is inherited from the base class, it's known as hierarchical inheritance. In hierarchical inheritance, all features that are common in child classes are included in the base class. For example, Physics, Chemistry, Biology are derived from Science class. Similarly, Dog, Cat, Horse are derived from Animal class.
- #10: When we make a class as friend, all its member functions automatically become friend functions.
- #11: When we make a class as friend, all its member functions automatically become friend functions.
- #12: When we make a class as friend, all its member functions automatically become friend functions.
- #13: When we make a class as friend, all its member functions automatically become friend functions.
- #14: When we make a class as friend, all its member functions automatically become friend functions.
- #15: When we make a class as friend, all its member functions automatically become friend functions.
- #16: When we make a class as friend, all its member functions automatically become friend functions.
- #17: When we make a class as friend, all its member functions automatically become friend functions.
- #18: When we make a class as friend, all its member functions automatically become friend functions.
- #19: When we make a class as friend, all its member functions automatically become friend functions.
- #20: When we make a class as friend, all its member functions automatically become friend functions.
- #21: When we make a class as friend, all its member functions automatically become friend functions.
- #22: When we make a class as friend, all its member functions automatically become friend functions.
- #26: Answer There is just one other son who takes the remaining £2000. The word elder means there are two. If there were more than two it would have been eldest.
- #27: Answer Carthy, Janine and Maria received $1220, $1320, and $1420 respectively. Joe received the same as his wife Carol, $1220. Hary received half again what his wife Janine did, $1980. Tommy got twice as much as his wife Maria, $2840. The word elder means there are two. If there were more than two it would have been eldest.