Object-Oriented Software Design

OOP vs C++

Inheritance

// exttime.h

enum ZoneType {EST, CST, MST, PST, EDT, CDT, MDT, PDT};

class ExtTime : public Time		// derived class
{
public:
    void Set( int hours, int minutes, int seconds, ZoneType timeZone );
    void Write() const;
    ExtTime( int initHrs, int initMins, int initSecs, ZoneType initZone );  
    ExtTime();				// Default constructor
        				//   setting time to 0:0:0 EST
private:
    ZoneType zone;
};

Constructor Initiator

ExtTime::ExtTime( int, int, int, ZoneType )
    : Time(initHrs, initMins, initSecs)		// use base class Time

Implementation file: exttime.cpp 

TestTime program

    testextt.cpp

Using Constructors and Destructors in Derived Classes

// FIG9_7.CPP
// Demonstrate when base-class and derived-class
// constructors and destructors are called.

#include <iostream.h>
#include "point2.h"
#include "circle2.h"

main()
{
   // Show constructor and destructor calls for Point
   {
      Point p(1.1, 2.2);
   }

   cout << endl;
   Circle circle1(4.5, 7.2, 2.9);
   cout << endl;
   Circle circle2(10, 5, 5);
   cout << endl;
   return 0;
}

Case Study

• Point
• Circle
• Cylinder

Multiple Inheritance

 
#include "base1.h"
#include "base2.h"

class Derived : public Base1, public Base2 
{
public:
	...
private:
	...
};