programming-for-dummies

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The Structure of a BASIC Program
Basic, which makes it possible to translate or port a Visual Basic program
into REALbasic so you can create a Linux or Macintosh version of a Visual
Basic program.
Both Visual Basic and REALbasic are the most prominent BASIC dialects that
offer structured programming and object-oriented programming. Two simpler
BASIC dialects that omit object-oriented features are Liberty BASIC (www.
libertybasic.com) for Windows and Chipmunk BASIC (www.nicholson.
com/rhn/basic) for the Macintosh. You can also visit the Run BASIC site
(www.runbasic.com) to practice writing BASIC programs through any
browser.
The Structure of a BASIC Program
In the original BASIC language, a program consisted of one or more commands
listed one after another, such as
PRINT “This is a simple BASIC program”
END
For creating simple programs, BASIC lets you get started right away by
focusing only on the commands you need. To create more complicated programs,
you can create a single main program and one or more subprograms.
The main program always runs first and determines when to run commands
stored in different subprograms.
In both Visual Basic (VB) and REALbasic (RB), there’s no main program.
Instead, a typical VB/RB program consists of a single project file that lists
the names of all files that make up that program. The three main types of
files used in a project are
✦ Window files
✦ Module files
✦ Class files
Using windows files
A window file contains a single window and various controls that appear on
that window, such as buttons, pull-down menus, or sliders. Besides containing
the user interface, a window file also contains subprograms that tell each
control, on that user interface, how to respond to an event.
Such subprograms, or event subprograms, tell the computer how to respond
when the user does something, such as click the mouse or move the mouse
over a control. Unlike a traditional BASIC program where the main program