Introduction To
Visual Basic 6
Announcements
 Thursday, Oct 9th, 7:30PM, C106
 Lloyd Douglas (NSF)
 Diversity in Science-Who needs it?
 5 extra credits.
 About the extra credit
 Please submit printed copy.
 Don’t hand in through blackboard
system or send email.
Programming language
 Programming is writing instructions
for a computer.
 Level of programming languages
 Machine language – 0s and 1s
 Intermediate languatge – assambly
language.
 High level language – BASIC, C++…
Interpreting or compiling
 How do computers handle the high
level language?
 Read and Interprete the code line by line
with an program called interpreter, e.g.
BASIC.
 Translate the language to machine code
(executable files) with a program called
compiler and run the program, e.g.
C++.
Visual basic has both Interpreter and Compiler.
History of BASIC
 Basic --- Beginners' All-purpose
Symbolic Instruction Code (May,
1964)
 MS-BASIC 2.0 (July, 1975)
 Visual Basic 1.0 (May,1991)
 Visual Basic 6.0 (July 1998)
Why do we learn Visual Basic
 It shares the same principles with
other programming languages.
 It is good when developing small and
handy utility programs.
 It is supported by Microsoft.
 It is powerful when integrated with
Excel and Word.
Six Steps in Programming
Problem Identification
Solution Design
Coding
Compiling with compiler or running
with interpreter
 Debugging
 Testing




Step 1 and 2: Problem
Identification and Design
 Identify what needs to be solved
 Make diagrams, and equations, etc
 Design: Analyze the problem and
develop an ALGORITHM and
FLOWCHART
Step 3: Source Code
 Creating “Source Code”
 Source Code is the instructions for the
computer written in Visual Basic
programming language
 In VB, source code is linked to an object
on the form
 Designing user interface is also part of
the coding.
Step 4a:Compiling
 Compiling converts Visual Basic
source code to “executable” machine
language - instructions the processor
can understand (1s and 0s)
 Creates .exe file
 Advantage:
 Fast and small
 Disadvantage:
 Debugging is inconvenient.
Step 4b: Interpreting
 Interpreting reads and runs one line
of code each time.
 You can find “Grammar errors” in this
stage.
 Advantage:
 Good for debugging
 Interpreter is easy to program.
 Disadvantage:
 Slow
Interpreting and Compiling in VB
Step 5: Debugging
 Debugging is removing the
“functional errors” from your program
 Running tells you where there are
errors
 Go back to source code and fix errors
 Save and re-run
 Repeat until errors are gone
Step 6: Testing and Running
 Try to run the program by pressing
the start button
 If it starts running, enter the answers
and/or click the buttons to test it
 Test your program with boundary and
special cases.
Visual Basic Programming
 VB is a programming language
that allows you to program in a
Windows environment
 You create a “Form” with several
“Objects”
 You set the properties of objects.
 You write event handler to response
to user’s input.
VB programming
Project
Form 1
Text box
Picture box
Form 2
Form 3
Button
Button
Objects
Text box
Objects
Definitions
 Form contains the Main Program
 Controls are user interface elements
(text boxes, commands) in the Form
 Forms and Controls are referred to as
OBJECTS
 Objects have PROPERTIES (features
you can change)
Forms in Visual Basic
 You create a form that is your
graphical user interface
 Has places to input values
 Has buttons to click
 Has other user interface elements,
e.g. Menu, scroll bar…
Objects in VB
 Everything in VB is
objects, forms,
buttons,…
 Three elements of
objects.
 Properties
 Methods
 Event handlers.
VB object
Properties (size,
Caption…)
Methods (Print…)
Event Handler
(Command1_Click())
Object: Dog
 Properties
 Height, weight, color, emotion (friendly,
hostile)…
 Methods
 Barking, biting, wagging, singing…
 Event handlers
 Owner coming in: call wagging, call singing,
emotion=friendly;
 Intruder coming in: call barking, call biting,
emotion=hostile.
Important Controls
 Text Boxes – area where you enter
text
 Command Buttons – you click on
them to do something
 Picture Boxes – Output your results.
Text Boxes
 Properties:








Name (of object)
Text (the words)
Alignment (left, right, middle)
Appearance
BackColor (background)
BorderStyle
Font
FontColor
Command Button
 Properties:




Name
BackColor
Style (This controls the backcolor)
Caption
Picture Boxes
 Properties
 Name
 Picture
 Methods
 Print
Definitions
Forms
properties
properties
properties
properties
Methods
properties
properties
properties
Handlers
Picture Box
properties
properties
properties
properties
properties
properties
properties
Methods
properties
properties
Command
Objects
Button
properties
properties
properties
Methods
properties
properties
Textbox
properties
properties
properties
properties
properties
properties
properties
Methods
properties
Label
properties
properties
properties
properties
properties
properties
properties
Methods
properties
properties
“Design time” and “Run time”
When you design you can use the
property window to set the property of
certain object.
When you run the program, you can
only use code to change the property
of that object.
Just a Bunch of Objects
 Q: Now that you have a bunch of
objects, how do you make them react
to your command?
 A: Sub Procedures
 Sub Procedures are the instructions
 Sub Procedures go with Events (Like
clicking a button)
How the test program works
How the test program works
You have got
letters.
Properties
Text box
Methods
Event Handler
User
Message
Dispatching
Block
Properties
Button
Methods
Event Handler
Properties
You have got
clicked.
Picture
Box
Methods
Event Handler
Making It Do Something
 Want program to change on an
“Event”
 Events:
 MouseDown
 MouseUp
 Click
 Need to create Sub Procedures
 Sub Procedure handles Event and
changes Properties of an Object
Sub Procedure
 Two Objects: Text1 and Command1
Sub Procedure:
Private Sub Command1_Click()
Text1.FontSize = 18
End Sub
 When Command1 is clicked, the
FontSize property of Text1 is
changed to 18
Sub Procedure
Private Sub CommButt_Click()
Text1.FontSize = 18
Text1.BackColor = vbBlue
Command1.Caption = "Get Some Now"
End Sub
Homework
 Read Chapters 1 & 2 in book
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Visual Basic - Michigan State University