This document discusses object-oriented programming concepts in C++, including inheritance, base classes, derived classes, and access specifiers. It provides examples of inheritance relationships between classes like Shape and its derived classes 2DShape and 3DShape. Inheritance allows code reuse and creation of class hierarchies where a derived class can inherit characteristics from its parent class. A derived class can override or extend the behavior of its parent class.

1. C++ OOP :: Inheritance14/10/20091Hadziq Fabroyir - Informatics ITS

2. Classes CharacteristicClasses are used to accomplish:Modularity► Scope for global (static) methodsBlueprints for generating objects or instancesClasses support Data encapsulation - private data and implementation.Inheritance-code reuse14/10/2009Hadziq Fabroyir - Informatics ITS2

3. InheritanceInheritance allows a software developer to derive a new class from an existing one.14/10/2009Hadziq Fabroyir - Informatics ITS3

4. InheritanceThe existing class is called the parent, super, or baseclass.The derived class is called a child or subclass.14/10/2009Hadziq Fabroyir - Informatics ITS4

5. Inheritance The child inherits characteristics of the parent.

6. The child has special rights to the parents methods and data.

7. Public access like any one else

8. Protected access available only to child classes (and their descendants).

9. The child has its own unique behaviors and data.14/10/2009Hadziq Fabroyir - Informatics ITS5

10. InheritanceInheritance relationships are often shown graphically in a classdiagram with the arrow pointing to the parent class.Inheritance should create an is-arelationship, meaning the child is a more specific version of the parent.14/10/2009Hadziq Fabroyir - Informatics ITS6AnimalBird

11. Examples: Base Classes and Derived Classes14/10/2009Hadziq Fabroyir - Informatics ITS7

12. Single / Multiple Inheritance ?Some languages, e.g., C++, allowMultiple inheritance, which allows a class to be derived from two or more classes, inheriting the members of all parents.C# and Java support only Single inheritance, meaning that a derived class can have only one parent class.14/10/2009Hadziq Fabroyir - Informatics ITS8

13. Class HierarchiesA child class of one parent can be the parent of another child, forming a class hierarchy14/10/2009Hadziq Fabroyir - Informatics ITS9

14. Classify It !14/10/2009Hadziq Fabroyir - Informatics ITS10

15. Class Hierarchies14/10/2009Hadziq Fabroyir - Informatics ITS11

16. Classify It !14/10/2009Hadziq Fabroyir - Informatics ITS12

17. Class Hierarchies14/10/2009Hadziq Fabroyir - Informatics ITS13

18. Class HierarchiesAn inherited member is continually passed down the lineInheritance is transitiveGood class design puts all common features as high in the hierarchy as is reasonable. Avoids redundant code.14/10/2009Hadziq Fabroyir - Informatics ITS14

19. References and InheritanceAn object reference can refer to an object of its class, or to an object of any class derived from it by inheritance.For example, if the 2DShape class is used to derive a child class called Triangle, then a 2DShape reference can be used to point to a Triangle object.2DShape myShape;myShape = new 2DShape();…myShape = new Triangle();14/10/2009Hadziq Fabroyir - Informatics ITS15

20. Overriding MethodsA child class can override the definition of an inherited method in favor of its ownThat is, a child can redefine a method that it inherits from its parentThe new method must have the same signature as the parent's method, but can have a different implementation.14/10/2009Hadziq Fabroyir - Informatics ITS16

21. Lect 28 P. 17Winter QuarterFunction OverloadingC++ supports writing more than one function with the same name but different argument lists. This could include:different data typesdifferent number of argumentsThe advantage is that the same apparent function can be called to perform similar but different tasks. The following will show an example of this.

22. Lect 28 P. 18Winter QuarterFunction Overloadingvoid swap (int *a, int *b);void swap (float *c, float *d);void swap (char *p, char *q);int main ( ) {int a = 4, b = 6 ;float c = 16.7, d = -7.89 ;char p = 'M' , q = 'n' ; swap (&a, &b) ; swap (&c, &d); swap (&p, &q); }

23. Lect 28 P. 19Winter QuarterFunction Overloadingvoid swap (int *a, int *b){ int temp; temp = *a; *a = *b; *b = temp; }void swap (float *c, float *d){float temp; temp = *c; *c = *d; *d = temp;}void swap (char *p, char *q){char temp; temp = *p; *p = *q; *q = temp;}

24. ComparisonOverloadingOverloadingdeals with multiple methods in the same class with the same name but different signaturesOverloadinglets you define a similar operation in different ways for different dataExample:int foo(string[] bar);intfoo(intbar1, floata);OverridingOverridingdeals with two methods, one in a parent class and one in a child class, that have the same signatureOverridinglets you define a similar operation in different ways for different object typesExample:class Base {publicvirtualintfoo() {} }class Derived {publicoverrideintfoo() {}}14/10/2009Hadziq Fabroyir - Informatics ITS20

25. Declaring a Derived ClassDefine a new class DerivedClass which extends BaseClassclass BaseClass {// class contents } class DerivedClass : BaseClass {// class contents }14/10/2009Hadziq Fabroyir - Informatics ITS21

26. Declaring a Derived Classclass A : base classaccess specifier B{ member access specifier(s): ... member data and member function(s); ...}Valid access specifiers include public, protected, and private14/10/2009Hadziq Fabroyir - Informatics ITS22

27. Public Inheritanceclass A : public B{ // Class A now inherits the members of Class B // with no change in the “access specifier” for} // the inherited members14/10/2009Hadziq Fabroyir - Informatics ITS23