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01 Overview
..Early computer languages were Command Line languages. A user
wrote a program, compiled it,
And
ran the EXE from the Command
Line (DOS prompt
-
C:
\
).
If
a visual
Interface
(such
As
a display graph
Or
location
To
Type
In
information) was needed, the user had
To
Write
the code
To
manipulate every
pixel
On
the screen that was needed
To
create the display.
Visual Basic greatly simplified this process by providing the capability
To
create user
Interface
items (windows, buttons, textboxes, etc.) easily
using just a mouse. All of the code
For
the user
Interface
Object
was pre
-
written
And
stored
In
"runtime"
files, which handled the details of interfacing
With
the Windows OS. All a user had
To
Do
was draw the button
And
Write
the code
To
respond
To
events such
As
a mouse click
Or
the
pressing of keys
On
the keyboard.
VB3 was the first version
To
achieve popularity. VB6 has been the most popular
of all
And
Is
still used by more programmers than the most recent edition
-
VB.net.
Another key feature of VB
Is
that it uses an
Event
-
driven model.
When
a VB program
starts it goes through some initialization
And
Then
basically waits
For
an
Event
To
occur.
Events are such things are mouse clicks
Or
button presses by the user. A VB program
consists primarily of the code which responds
To
these events.
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