programming-for-dummies

258
Real-Life Programming Examples
multiplies them by 2, and uses that result for the cow object’s new X and Y
coordinates.
Not every object-oriented language requires you to identify polymorphic
subprograms. Some languages let you inherit and modify subprograms without
identifying them first.
So running the main program would now print the following on-screen:
X-location = 1
Y-location = 1
New X-location = 48
New Y-location = 18
The cow’s initial IQ is 45
The cow’s IQ is now 81
Notice that the main program now uses the Move subprogram stored in
the human class, which multiplies each number by 2. So the cow.move
(24, 9) command sets the cow’s x_coordinate to 48 (24 * 2) and the
y_coordinate to 18 (9 * 2).
Although these examples use C++, the basic steps to using objects remain
the same:
1. Create a class that defines the data and subprograms used by an
object.
2. Create one or more additional classes that inherit code from another
class.
3. Use polymorphism to rewrite code inherited from another object.
4. Declare an object as a specific class type.
5. Use an object’s subprograms to manipulate that object’s data.
Object-oriented programming can help you design large programs faster, but
ultimately, your own skill as a programmer determines the quality of your
programs.