Lec 30.31 - inheritance
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This document discusses inheritance in C++. It defines inheritance as the process of creating new classes (derived classes) from existing classes (base classes). Inheritance allows for code reusability and increases a program's reliability. The document provides examples of using inheritance to create derived shape classes like Rectangle and Triangle from a base Polygon class. It also covers syntax for defining derived classes using the colon operator and access specifiers. Finally, it discusses overriding base class member functions in derived classes.
Lec 30.31 - inheritance
- 1. Chapter: 09 Inheritance Lecture: 30 & 31 Date: 08.10.2012
- 2. Inheritance: Base and Derived Classes Inheritance is the process of creating a new classes (derived classes) from existing classes (based classes).
- 3. Inheritance: Base and Derived Classes
- 4. Inheritance: Advantages Permits code reusability Reusing existing code saves time and money and increases a program’s reliability
- 5. Inheritance: Shapes Polygon Rectangle Triangle
- 6. No-Inheritance: Shapes class Rectangle{ Polygon private: int numVertices; int xCoord, yCoord; public: Rectangle void set(int x, int y, int nV); Triangle int area(); }; class Polygon{ private: class Triangle{ int numVertices; private: int xCoord, yCoord; int numVertices; int xCoord, yCoord; public: public: void set(int x, int y, int nV); void set(int x, int y, int nV); int area(); int area(); }; };
- 7. Inheritance: Shapes class Polygon{ Polygon protected: int numVertices; float xCoord, yCoord; public: void set(int x, int y, int nV); }; Rectangle Triangle class Rectangle : public Polygon{ public: int area(); };
- 8. Inheritance: Shapes class Polygon{ Polygon protected: int numVertices; float xCoord, yCoord; public: void set(float x, float y, int nV); }; Rectangle Triangle class Triangle : public Polygon{ class Rectangle : public Polygon{ public: public: int area(); float area(); }; };
- 9. Inheritance: Syntax Syntax: class DerivedClassName : access-level BaseClassName where access-level specifies the type of derivation private by default, or Public Any class can serve as a base class Thus a derived class can also be a base class
- 10. Inheritance: Syntax Syntax: class DerivedClassName : access-level BaseClassName Example: class BaseClass { } class DerivedClass: public BaseClass { }
- 11. Access Specifier without Inheritance
- 12. Access Specifier with Inheritance
- 14. Overriding member functions Member functions in a derived class can have the same names as in the base class When the same function exists in both the base and derived classes, the function in the derived class will be executed. In order to call a function in the base class use the use the scope resolution operator, e.g., Stack :: push() Name Scope Call to a member function (base class) resolution in base class
- 15. Stack Applications Memory management Tower of Hanoi
- 16. Stack Applications Converting a decimal number to binary
- 17. Inheritance: Shapes x class Point{ Point y protected: int x, y; public: Circle 3D-Point void set (int a, int b); x x }; y y r z class Circle : public Point{ class 3D-Point: public Point{ private: private: double r; int z; }; };