C++ Design Pattern

Week One (Overview of Course): Step Assignments: About 6 Design Assignments: About 10

To Do: Read Chapter One in Object-Oriented Modeling Do Step 1 of the Assignment

Week Two: • Review basic OOP Concepts • Review Inheritance and Polymorphism • Work on “Square” program • Objects vs Classes • Constant Functions and Constructors • Pointers

Work on “Square” program

Let’s say we want to describe a square

Heres the header file

#ifndef CSQUARE_H_

#define CSQUARE_H_



class CSquare{ 
    private:

        int mX; // Center x
        int mY; // Center y
        int mWidth; // Width of the square
    public:

        CSquare() : mX(0), mY(0), mWidth(100){}

        int GetX() const  {
            return mX;
        }
        void SetX(int x)
        {
            mX = x;
        }
        int GetY() const {
            return mY;
        }
        void SetY(int y)
        {
            mY = y;
        }

        int GetWidth() const {
            return mWidth;
            }
        void SetWidth(int w)
        {
            mWidth = w;
        }
    
}

#endif /* CSQUARE_H_ */

What do these do?

• These are the #include Guard

#ifndef CSQUARE_H_
#define CSQUARE_H_

// code
#endif /* CSQUARE_H_ */

Objects vs Classes

Now what is the difference between the two?

• Class: A type, which defines what an object will contain

• Object: An instance of the class

Constant Functions and Constructors

• const funciton is not allowed to change the object and is guaranteed not to.

• {} is the code to run to construct an object of our class CSquare

Inheritance

• Inheritance creates new classes based on the classes that have already been defined. The capabilities of the base class are inherited by the dervied class

Advantages of Inheritance

• Factors out code that is common in multiple classes
  • Dervied class inherits noth function and data members from the base class
  • Dervied class can add additional functions or data memebers
  • Dervied class can override inherited function memebers with new methods

Example

class CShape{ 
    private:
        int mX; // Center x
        int mY; // Center y
  
    public:

        CShape() : mX(0), mY(0),){}

        int GetX() const  {
            return mX;
        }
        void SetX(int x)
        {
            mX = x;
        }
        int GetY() const {
            return mY;
        }
        void SetY(int y)
        {
            mY = y;
        }    
}

// Two Derived Classes

// Square Class
class CSquare :public CShape
{
  private:
    int mWidth; // Width of the square
  public:
    CSquare(): mWidth(100){}
    int GetWidth() const 
    {
      return mWidth;
    }
    void SetWidth(int w)
    {
      mWidth = w;
    }
}

// Oval Class

class COval :public CShape
{
  private:
    int mWidth;
    int mHeight;

    public:
      COval :mWidth(100), mHeight(100) {} // constructor

      int GetWidth() const
      {
        return mWidth;
      } 
      int GetHeight() const
      {
        return mHeight;
      }
      void SetSize(int w, intg h)
      {
        mWidth = w;
        mHeight = h;
      }
}

Pointers

Week Three

Polymorphism in C++

Virtual Functions