Name:
S2
Chapter 1
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Chapter 1 / Ideas of Programming / P.1
Ideas of Programming
1.1 What is a program?
In S1, you should have learned what a program is.
A program is a set of instructions that tells a computer what to do.
In order a computer to do a job for us, the instructions in the program must be:
1. correct
2. in the proper order; and
3. written in a suitable programming language.
Is a program a computer hardware or software? ________________
1.2 How Programming Works
When a programmer writes a program, he/she is telling the computer how to complete the job.
1.3 What is A Programming Language?
People express themselves using a language that has
many words. But the computer can only understand
machine language. It use a simple language that consists
of only 1s and 0s, with a 1 meaning "on" and a 0 meaning
"off." Trying to talk to a computer in its own language
would be like trying to talk to your friends by using
Morse code—it can be done, but it is difficult.
A programming language acts as a translator between you and the computer. Rather than
learning the computer's native language (known as machine language), you can use a
programming language to instruct the computer in a way that is easier to learn and understand.
A specialized program known as a compiler takes the instructions written in the programming
language and converts them to machine language. This means that as a Visual Basic programmer,
you do not have to understand what the computer is doing or how it does it. You just have to
understand how the Visual Basic programming language works.
Chapter 1 / Ideas of Programming / P.2
1.4 Idea of Translators
Source program
which is written by human
in certain programming
Object program
Translator
language
which is machine language
Execution
that the computer
understands
1.5 Examples of Programming languages
A
BASIC (Beginner’s All-purpose Symbolic Instruction Code)
BASIC is designed to provide beginners with an easy-to-learn programming language.
B
Logo
We can use Logo to draw attractive graphics. It is usually used to teach programming
in schools
REPEAT 4 [FD20 RT 90]
C
Pascal
Pascal is designed mainly as a tool for teaching programming concepts and good
programming style.
program HelloSchool(input,output);
var
name: string;
begin
name := ‘Tang Hin’;
writeln(‘Hello , ’, name)
end.
D
Visual Basic
Visual Basic is similar to BASIC in its instructions. It uses graphics tools to construct
programs that can be run in the Windows environment.
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
textbox1.text = "Hello"
End Sub
End Class
Name:
Chapter 2
S2
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Chapter 2 / Start to Program! / P.1
Start to Program!
2.1 Download VB 2010
A tutorial web site on how to download and install:
http://pcnoproblem.twbbs.org/vb2010-express/
Microsoft’s Official Site to download VB2010:
http://www.microsoft.com/express/Downloads/
Remember to choose the English version to download.
2.2 Create and Save a new project
1.
Click “New Project”
2.
Choose “Windows
Forms Application”
Chapter 2 / Start to Program! / P.2
Form Designer
Toolbox:-
Solution
Common
Explorer
Controls
Properties
Window
When some of the above boxes disappear, you can click the buttons to show them.
In the above screen, object Form1 is being edited.
To save the project, it is good to choose
“Save All”.
For the first time you click “Save All”,
your are required to choose a folder for
storing your project.
In the above example, all files in “E:\VB_Projects\WindowsApplication1” are necessary!
Chapter 2 / Start to Program! / P.3
Find “Button” in Toolbox, and then put it into the form.
You can then adjust the properties of the button and the form at Design Time.
Adjust the size of the
Adjust the size of the
form.
button. (Called Button1)
Change the Text property
to “Go.”
Double click the button object, you should see that some VB codes appear.
It means when Button1 is clicked, do the procedure.
The event triggered (觸發) is “Button1.Click”.
Public Class Form1
Private Sub Button1_Click(...) Handles Button1.Click
MsgBox("Hello")
End Sub
Insert this line of code
End Class
2.3 Open an existing project
1.
2.
Click “Open Project”
Browse into the folder
and you should see a
“Solution File”.
Choose this file and
then click “Open”.
Chapter 2 / Start to Program! / P.4
2.4 Making a simple web browser
Design the following form by putting some controls on it.
Button1
TextBox1
WebBrowser1
Add the following code:
Public Class Form1
Private Sub Button1_Click(...) Handles Button1.Click
WebBrowser1.Navigate(TextBox1.Text)
End Sub
End Class
To run the program click this “Play” button
Question 1: What is the event triggered in the above code? _____________________________
Question 2: What happens when “http://www.google.com” is entered in TextBox1 and then
Button1 is clicked?
_____________________________________________________________________________
Name:
S2
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Chapter 3
Working with Controls
Chapter 3 / Working with Controls / P.1
P.
3.1 Using Toolbox to design User Interface
To insert a control into your form, you just need to
drag the control from the Toolbox and drop it into
the form. You
ou can reposition and resize it as you
like.
If the toolbox
disappears, click
this button to make
it show again.
Some common controls include:
Textbox
Label
Button
PictureBox
By adding controls into the form, you can design
the User Interface of the program.
Note: Such kind of user interface that contains graphics is
called Graphical User Interface (GUI).
(GUI)
i.e. We use VB2010 to create GUI programs.
Basically, a Windows Forms Application program consists of the following:
Form
Control
Setting the properties of the form and controls
Complete program codes for events that trigger program behavior.
behavior
3.2 Changing the Properties
The properties of the controls (objects) can be set at design time and run time.
time
At design time, the Properties Window shows the properties of the selected control. Some
commonly used properties are listed on the next page.
Program codes can be written to change the properties at run time. The syntax is shown below.
Object.Property = New_Value
e.g.1
e.g.2
Label1.Text = “Hello!”
Button1.BackColor
BackColor = Color.Red
Chapter 3 / Working with Controls / P.2
Setting Properties at design time using Properties Window.
Common Properties of Common Controls:
Common Properties of TextBox
Common Properties of Label
Common Properties of Button
Text
Text
Text
TextAlign
TextAlign
TextAlign
Width / Height
Width / Height
Width / Height
Left / Top
Left / Top
Left / Top
Visible
Visible
Visible
Enabled
Enabled
Enabled
Font.size
Font.size
Font.size
ForeColor / BackColor
ForeColor / BackColor
ForeColor / BackColor
(Readonly)
AutoSize
(PasswordChar)
Common Properties of Form:
Text
Width / Height
Left / Top
Visible
Enabled
Font.size
ForeColor / BackColor
StartPosition / WindowState
Chapter 3 / Working with Controls / P.3
P.
Chapter 3 / Working with Controls / P.4
Example codes:
Private Sub Button1_Click(...) Handles Button1.Click
Label1.BackColor = Color.Red
Label1.ForeColor = Color.Blue
Picturebox1.Visible = False
Button1.Enabled = False
Button1.Text = “Don’t click me!”
Me.Text = “Example”
End Sub
Note:
1. Spell color in US style. (UK: Colour , US: Color)
2. To specify a color, we need to write Color.XXX, where XXX is the name of the color.
3. When Visible property is set to false, the control (object) is invisible. (disappears)
4. When Enabled property is set to false, the control (object) cannot be used.
5. To specify text property, a pair of double quotation mark (“ … ”) is needed for the string.
6. When the form itself is specified, the word Me is used.
Name:
Chapter 4
S2
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Chapter 4 / Events / P.1
Events
4.1 Event-driven Programming Language
VB2010 is a kind of event-driven programming language.
An event refers to an action, such as the user clicking on a button.
Writing VB programs takes most of the time writing codes for event procedures.
Public Class Form1
Private Sub Form1_Load(...) Handles MyBase.Load
Marks the
start and end
End Sub
of all
procedures in
Private Sub Button1_Click(...) Handles Button1.Click
Form1
End Sub
End Class
Name of event procedures
Name of events
The outline of the event procedures can be created by Double-clicking on the control.
The default event procedure is created.
To add event procedures of other events, choose the event in the selection box at the top of code
editor.
Chapter 4 / Events / P.2
4.2 Common Events for a form
Private Sub Form1_Click(...) Handles Me.Click
‘ Triggers when the form is clicked
End Sub
Private Sub Form1_DoubleClick(...) Handles Me.DoubleClick
‘ Triggers when the form is double-clicked
End Sub
Private Sub Form1_MouseEnter(...) Handles Me.MouseEnter
‘ Triggers when a mouse moves into the form
End Sub
Private Sub Form1_Load(...) Handles MyBase.Load
‘ Triggers when the form is loaded
End Sub
Note: The default event for a form is Load.
4.3 Common Events for common controls
Button
Label
TextBox
*
*
DoubleClick
MousrEnter
MouseLeave
TextChanged
*
Click
(* indicates the default event)
Name:
S2
Chapter 5
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Chapter 5 / Input and Output / P.1
Input and Output
5.1 Using TextBox to accept input
Activity 1:
Private Sub Button1_Click(...) Handles Button1.Click
TextBox2.Text = TextBox1.Text
End Sub
TextBox1
Button1
Run the program, enter some words in
TextBox1 and click Button1
TextBox2
Describe your observation:
Ans: ________________________________________________________________________
Activity 2:
Create the following form which contains 2 text boxes, 1 button and 1 label.
Complete the program codes for the button.
Private Sub ___________________________(...) Handles ___________________________
______________________________________________________________________________
End Sub
Note:
You can use the symbol ‘+’ or ‘&’ to join 2 strings. E.g.
TextBox1.Text + TextBox1.Text
or
TextBox1.Text & TextBox1.Text
However, ‘&’ is safer.
Chapter 5 / Input and Output
/ P.2
5.2 Using Variables to store data temporarily
Type
Integer
Stores
Whole numbers (-32768 to +32767)
Single / Double Decimal numbers
Boolean
Logical values (TRUE or FALSE)
String
Text information
E.g.
Dim num as Integer
Dim money as Double
Dim isWealthy as Boolean
Dim studentName as String
Activity 3:
Create a form that contains 1 text box, 1 button and 1 label.
Write the following code
1
2
3
4
Dim S2 As String
Private Sub Form1_Load(...) Handles MyBase.Load
S2 = "Hello, nice to meet you"
End Sub
5
6
7
Private Sub Button1_Click(...) Handles Button1.Click
Label1.Text = TextBox1.Text & S2
End Sub
Run the program, enter some words into TextBox1 and click Button1
Describe your observation.
Note:
If line 1 is MOVED to between line 2 and line 3, the variable S2 is only usable within Form1_Load
procedure. Therefore, in the procedure Button1_Click, S2 contains nothing (null). So, Label1 will
only show the text in TextBox1.
Name:
S2
Chapter 6
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Chapter 6 / Arithmetic Operators / P.1
Arithmetic Operators
6.1 Common Arithmetic Operators
Operator
Meaning
Example
Result
+
To add two numbers
3+8
11
-
To subtract two numbers
10-15
-5
*
To multiply two numbers
3*8
24
/
To divide two numbers and return the result in decimal number
10/4
2.5
\
To divide two numbers and return the result in integer
10\4
2
To divide two numbers and return the remainder
4 mod 3
1
To find the exponential power
4^2
16
Mod
^
Activity 1:
Find out the value of the following:
Input
Output
3+6
3–6
15/7
15\6
15 mod 6
3*6
2^5
5^2
3 ^ (5-2)
6.2 Operators Precedence
Operators
Precedence
Exponential (^)
Highest
(Evaluated first)
Negation (-)
Multiplication (*) and division (/)
Integer division (\)
Modulo (mod)
Addition (+) and subtraction (-)
String concatenation (&)
Lowest (Evaluated last)
Chapter 6 / Arithmetic Operators
/ P.2
Activity 2:
Find out the value of the following:
Input
Output
2+3*5
2+9/3
1-3+9*2-1
21/3+4/2
3+5/2
(3+5)/2
2^3+1
3+9\2
6.3 Use of VAL function
When user input some data in TextBox1, TextBox1.Text is string type in nature, i.e.
is NOT a number.
Therefore, a function called VAL is needed to convert string type data into number.
TextBox1.Text
Activity 3:
Design a form as shown.
Write the following code:
1
2
3
Private Sub Button1_Click(...) Handles Button1.Click
TextBox2.Text = TextBox1.Text + TextBox2.Text
End Sub
Input numbers in the 2 TextBoxes and click the button, what happens?
Ans: ________________________________________________________________________
How can you amend the code so that the program works properly?
Line: _________ Amended Code: ________________________________________________
Name:
S2
Chapter 7
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Chapter 7 / Flow Control(1) / P.1
Flow Control(1)
6.1 Decision Making
A logical expression can give Boolean result, i.e. the result can be True or False.
6.2 Relational Operators
Fill in the missing column ‘Opposite’. The first one has been done for you.
Relational
Operators
Meaning
Example
Result
=
Equal to
9 = 11
False
>
Greater than
11 > 9
True
<
Less than
11 < 9
False
>=
Greater or equal
15 >= 15
True
<=
Less or equal
9 <= 15
True
<>
Not equal
9 <> 9
False
Opposite
Conversion to program codes
Test
1. Is Peter(PHeight) taller than Mary(MHeight)
2. Is Linda’s age (LAge) not equal to May’s age
3. The passing mark is 50. Has Gigi(GMark) failed the
test?
4. It is free to travel by MTR for a person with height 1m
or below. Is it free for Kitty(KHeight) to travel by MTR?
5. Is X an even number?
Conditions with operators
<>
Chapter 6 / Arithmetic Operators
/ P.2
6.3 Conditional Statements
VB Syntax:
E.g.
If condition Then
If Val(Text1.Text)=1 Then
Text2.Text= “It is one!”
Instructions1
End if
Instructions2
End If
VB Syntax:
E.g.
If condition Then
Private Button1_Click(...) Handles Button1.Click
Instructions1
Instructions2
……
firstnum = Label1.Text
secondnum = Label2.Text
total = firstnum + secondnum
Else
Instructions3
If total = Val(TextBox1.Text) Then
Instructions4
Label3. Text = “Correct! Well Done”Else
……
Label3. Text = “Wrong! Try again”
End If
End If
End sub