1. Introduction To Visual Basic 6

2. Announcements Thursday, Oct 9th, 7:30PM, C106 About the extra credit
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 .

3. 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++…

4. 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.

5. 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)

6. 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.

7. Six Steps in Programming
Problem Identification
Solution Design
Coding
Compiling with compiler or running with interpreter
Debugging
Testing

8. 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

9. 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.

10. 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.

11. 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

12. Interpreting and Compiling in VB

13. 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

14. 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.

15. 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.

16. VB programming Project Form 1 Form 2 Form 3 Button Text box Button
Picture box
Objects
Objects

17. 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)

18. 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…

19. 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())

20. Object: Dog Properties Methods Event handlers
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.

21. Important Controls Text Boxes – area where you enter text
Command Buttons – you click on them to do something
Picture Boxes – Output your results.

22. Text Boxes Properties: Name (of object) Text (the words)
Alignment (left, right, middle)
Appearance
BackColor (background)
BorderStyle
Font
FontColor

23. Command Button Properties: Name BackColor
Style (This controls the backcolor)
Caption

24. Picture Boxes
Properties
Name
Picture
Methods
Print

25. Definitions Objects Command Button Forms Textbox Picture Box Label
properties
properties
Textbox
properties
properties
properties
properties
properties
Methods
Methods
properties
Methods
properties
properties
properties
properties
properties
properties
properties
properties
properties
Handlers
properties
properties
properties
Methods
properties
Picture Box
Label
properties
properties
properties
properties
properties
properties
properties
properties
properties
properties
properties
Methods
properties
properties
properties
properties
Methods
properties
properties
properties

26. “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.

27. 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)

28. How the test program works

29. How the test program works
You have got letters.
Properties
Text box
Methods
Message
Dispatching
Block
Event Handler
User
Properties
Button
Methods
Event Handler
Properties
Picture
Box
You have got clicked.
Methods
Event Handler

30. 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

31. 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

32. Sub Procedure Private Sub CommButt_Click() Text1.FontSize = 18
Text1.BackColor = vbBlue
Command1.Caption = "Get Some Now"
End Sub

33. Homework
Read Chapters 1 & 2 in book