Teach Yourself Borland C++ in 14 Days - portal

NOTE
Totally Immersed: C++ Classes and Object-Oriented Programming
button->Caption = “New Button”;
button->Left = 100;
button->Top = 100;
button->Show();
// more code
}
In this code you can see that this is used in the constructor (this sets the Owner property of
the button, but I’ll get into that later when I cover VCL components on Day 8, “VCL
Components”) and also that it is assigned to the Parent property of the newly created button.
This will be how you use the this pointer the vast majority of the time in your C++Builder
applications.
Earlier I said that static member functions can’t access class data
members. This is true because static member functions do not have a
hidden this parameter as regular class member functions do. Without
this, a function cannot access class members.
Don’t get too hung up on this…er, this (whatever!). When you begin to use VCL, it will
quickly become clear when you are required to use this in your C++Builder applications.
An Example
Right now it would be nice if you had an example that uses classes. The following listings
contain a program that implements classes. This program allows you to play air traffic
controller by issuing commands to three aircrafts. Listing 4.1 is the header for the Airplane
class, Listing 4.2 is the source code for the Airplane class, and Listing 4.3 is the main program.
Listing 4.1. AIRPLANE.H.
1: //------------------------------------------------------
2: #ifndef airplaneH
3: #define airplaneH
4: #define AIRLINER 0
5: #define COMMUTER 1
6: #define PRIVATE 2
7: #define TAKINGOFF 0
8: #define CRUISING 1
9: #define LANDING 2
10: #define ONRAMP 3
11: #define MSG_CHANGE 0
109
continues
4