Expert: Zlatko - 11/27/2010

Question
Hi Zlatko

I have 2 classes, Rectangle & Block. I am trying to make than communicate. However there are a few errors during program compile.


#include <iostream>
using namespace std;

//class Rectangle
class Rectangle
{
private:
  int length;
  int width;
public:
  int getData(int,int);
  void showRectangle();
  int computeArea();
};


int Rectangle::getData(int len, int wid)
{
  length = len;
  width = wid;
}

void Rectangle::showRectangle()
{
  cout <<"Dimensions are " << length << "by "
      << width << endl;

}

int Rectangle::computeArea()
{
  int area = length * width;
  cout << "Area is " << area << endl;

}

//class Block
class Block : public Rectangle
{
private:
  int height;
public:
  int getData(int,int);
  void showBlock();
  int computeArea();
};

int Block::getData(int len, int wid, int ht)
{
  Rectangle::getData(len, wid);
  ht = height;
}

void Block::showBlock()
{
  cout << "Height " << height << endl;
  showRectangle();
  cout << endl;
}

int Block::computeArea()
{
  int area = length * width * height;
  cout << "Volume is " << area << endl;
}

//main function
int main()
{
  Rectangle square;
  square.getData(4,5);
  cout << endl << "Rectangle..." << endl;
  square.showRectangle;
  square.computeArea();
  
  Block cube;
  cube.getData(2, 4, 6);
  cout << "Block..." << endl;
  cube.showBlock();
  cube.computeArea();
}  

Answer
Hello Steve.

Below is the corrected program. I am not including a text explanation of what I did. I am trying something new. You can watch a video of the program being corrected and hear my explanations by going to this site:

http://www.divshare.com/download/13343006-54b

I recommend you watch in full screen mode.

Please do let me know if the video is watchable, or if it needs too much bandwidth.

#include <iostream>
using namespace std;

//class Rectangle
class Rectangle
{
protected:
   int length;
   int width;
public:
   Rectangle();
   void setData(int,int);
   void showRectangle();
   int computeArea();
};

Rectangle::Rectangle()
{
   length = 0;
   width = 0;
}

void Rectangle::setData(int len, int wid)
{
   length = len;
   width = wid;
}

void Rectangle::showRectangle()
{
   cout <<"Dimensions are " << length << "by "
       << width << endl;

}

int Rectangle::computeArea()
{
   int area = length * width;
   cout << "Area is " << area << endl;
   return area;
}

//class Block
class Block : public Rectangle
{
private:
   int height;
public:
   Block();
   void setData(int len, int vid, int ht);
   void showBlock();
   int computeVolume();
};

Block::Block()
{
   height = 0;
}

void Block::setData(int len, int wid, int ht)
{
   Rectangle::setData(len, wid);
   height = ht;
}

void Block::showBlock()
{
   cout << "Height " << height << endl;
   showRectangle();
   cout << endl;
}

int Block::computeVolume()
{
   int volume = length * width * height;
   cout << "Volume is " << volume << endl;
   return volume;
}

//main function
int main()
{
   Rectangle square;
   square.setData(4,5);
   cout << endl << "Rectangle..." << endl;
   square.showRectangle();
   square.computeArea();

   Block cube;
   cube.setData(2, 4, 6);
   cout << "Block..." << endl;
   cube.showBlock();
   cube.computeArea();
   cube.computeVolume();
}