25-10-2012, 04:07 PM
MS Visual Basic 6
VB6 0 Intro.ppt (Size: 1.43 MB / Downloads: 184)
What is Visual Basic?
Kemeny and Kurtz – Dartmouth College 1964
For students – simple interpreted
Many versions since
MS VB versions – more power not so simple
VBScript VBA .NET framework
RAD especially of user interface
VB is not..
Vendor independent
Platform independent
Based on a constant language definition
Separated definition and IDE implementation
Well documented
(IMO) suitable for very large projects which must be maintained over a long period of time
Building an application - steps
Commercial – data driven – waterfall model – project management
Science/engineering – underlying data and physical model, algorithms, testing
In VB – RAD – focus on user interface prototyping and review.
Building an application - controls
Buttons, text boxes, labels, check boxes..
VB 'control' = user interface widget
Some invisible – timer
Controls have properties eg background color
Three kinds –
standard
non-standard MS controls (common dialog, tab) and 3rd party
ActiveX controls written in-house
Building an application - modularity
Spaghetti programming, structured programming, OOP = increasing modularity
In VB application constructed from modules = files in project-
Form modules
BASIC modules
Class modules
Private and public control interaction between modules
Event-driven programming
Standard approach for GUIs
Contrast with old character interfaces – program determines what happens
In GUI, the user triggers what application does (mostly)
Event examples are key press, mouse move, timer timeouts
Correspond to native Windows Messages (next slide)
Event handler = a subroutine which will execute when that event happens