Sams Teach Yourself C++ in 21 Days

Understanding Object-Oriented Programming 167

6

9:

10: itsUpperLeft.SetX(left);

11: itsUpperLeft.SetY(top);

12:

13: itsUpperRight.SetX(right);

14: itsUpperRight.SetY(top);

15:

16: itsLowerLeft.SetX(left);

17: itsLowerLeft.SetY(bottom);

18:

19: itsLowerRight.SetX(right);

20: itsLowerRight.SetY(bottom);

21: }

22:

23:

24: // compute area of the rectangle by finding sides,

25: // establish width and height and then multiply

26: int Rectangle::GetArea() const

27: {

28: int Width = itsRight-itsLeft;

29: int Height = itsTop - itsBottom;

30: return (Width * Height);

31: }

32:

33: int main()

34: {

35: //initialize a local Rectangle variable

36: Rectangle MyRectangle (100, 20, 50, 80 );

37:

38: int Area = MyRectangle.GetArea();

39:

40: std::cout << “Area: “ << Area << “\n”;

41: std::cout << “Upper Left X Coordinate: “;

42: std::cout << MyRectangle.GetUpperLeft().GetX();

43: return 0;

44: }

Area: 3000

Upper Left X Coordinate: 20

Lines 3–14 in Rectangle.hpp(Listing 6.8) declare the class Point, which is

used to hold a specific x- and y-coordinate on a graph. As written, this program

doesn’t use Pointsmuch; however, other drawing methods require Points.

OUTPUT

LISTING6.9 continued

ANALYSIS