Accessing instance variables

You can read the values of an instance variable using the same syntax we used to write them:

double dX = MyPoint.dX;

The expression MyPoint.dX means “go to the object named MyPoint and get the value of dX”. In this case we assign that value to a local variable named dX. Notice that there is no conflict between the local variable named dX and the instance variable named dX. The purpose of dot notation is to identify which variable you are referring to unambiguously.

You can use dot notation as part of any C++ expression, so the following are legal.

Max.SetPos ( MyPoint.dX + 5.0, MyPoint.dY * 1.1 );

double dDistance =

Sqrt ( MyPoint.dX * MyPoint.dX + MyPoint.dY * MyPoint.dY );

In this sample code, the first line changes the position of a WCM character and second line calculates the distance of a point from cartoon's origin. Note that this code as written would not be part of a class definition. If it were, the distance variable would be written as MyPoint.dDistance .