Programming with…
Visual Basic
Table of Contents
Variables................................................................................................................... 3
Variable Data Types ...................................................................................................................3
The Visual Basic opening screen............................................................................ 4
What are Labels? .................................................................................................... 5
What are Text Boxes? ............................................................................................. 6
What are Form Properties? ................................................................................... 7
Project 1
VB is Fun ............................................................................................ 8
How to start a new project ..........................................................................................................8
How to create a Label .................................................................................................................8
How to create a Command Button ..............................................................................................8
How to write code .......................................................................................................................9
Saving a Visual Basic Program ............................................................................ 10
Project
The Personal Computer .................................................................... 11
How to create a Label ...............................................................................................................11
How to place graphic images on the form ................................................................................11
How to use Copy to add two more command buttons ..............................................................11
How to write code behind the buttons to move the pointer when you click any of the three
buttons. ......................................................................................................................................12
How to run your program to see if it all works .........................................................................12
Structure Diagrams ............................................................................................... 13
Background ...............................................................................................................................13
Sequence ...................................................................................................................................13
Exercises ...................................................................................................................................13
Project
Simple Addition ................................................................................. 14
How to create a Label ...............................................................................................................14
How to select the TextBox tool from the tool box. ..................................................................15
Converting Celsius to Fahrenheit .............................................................................................16
Making the conversion program respond to the Enter key rather than the command button ...16
Making the program more versatile ..........................................................................................17
Formatting numbers ..................................................................................................................18
Selections and Decisions ....................................................................................... 19
Loops....................................................................................................................... 20
For… Next loop ........................................................................................................................20
Positive step of one from a given number ................................................................................20
Displays 1 2 3 4 5 6 ..................................................................................................................20
Negative step of minus one from a given number ....................................................................20
Displays 6 5 4 3 2 1 ..................................................................................................................21
Positive step of plus two from a given number ........................................................................21
Displays 0 2 4 6 8 10 ................................................................................................................21
Project … Exploring loops .......................................................................................................21
Problems ...................................................................................................................................22
Strings – String Functions .................................................................................... 23
Simple programs to illustrate string functions ................................................... 24
Page 1
Project …Reversing a string .....................................................................................................24
Project …Joining Strings – Concatenation ...............................................................................26
Project … Splitting Strings .......................................................................................................27
Project …Word Counter ...........................................................................................................28
Visual Basic – Arrays ............................................................................................ 29
General Area .............................................................................................................................29
Printing out data from an array .................................................................................................30
Printing the data in reverse order ..............................................................................................30
Carrying out a simple sequential search ...................................................................................30
Sorting data in an array .............................................................................................................31
Diagram to show Sorting ..........................................................................................................32
Page 2
What is Visual Basic?
Visual Basic is a programming language that allows you to create your own software with the look of
Windows programmes that you are familiar with. It is the most common and easiest to learn of modern
computer languages
Visual Basic is also able to add additional features to Microsoft Office applications. When you write a Macro
in Excel it is actually created for you using Visual Basic.
Definition
The word visual in Visual Basic means graphical, easily seen such as pictures and symbols that you can click
on and drag.
BASIC is short for Beginners All purpose Symbolic Instruction Code. BASIC was originally developed to
make it possible for home users to program PCs.
BASIC is considered to be a high level language because BASIC code uses a simple set of English words and
symbols to give instructions to the computer, not the low level instructions that deal with the zeros and ones
that the computer understands.
Event
Driven
Language
Visual Basic is also an Event Driven language. Event driven languages allow you to choose what you do
rather than have to respond to a series of questions the computer dictates. Event driven languages such as
Visual Basic are called Object Oriented Languages or OOLs.
There are two parts to creating Visual Basic applications.
1. You firstly place the objects (buttons etc) on a form then
2. Secondly write the code that is hidden behind these buttons. The code makes the buttons respond in the
way you want them to.
Variables
Variables are placeholders used to store values; they have names and data types. The data type of a variable
determines how the bits representing those values are stored in the computer's memory. When you declare a
variable, you can also supply a data type for it. All variables have a data type that determines what kind of data
they can store.
You can think of variables as containers, and you choose to put data in the most suitable container. You would
not put a small object in a large box or try to stuff a large object into a small box.
The following variables are available in visual basic.
Variable Data Types
Data type
Boolean
Byte
Currency
Date (Time)
Double
Integer
Long
Single
String
Prefix
bln
byt
cur
dtm
dbl
int
lng
sng
str
Example
blnWillgo
bytRasterData
curMoneyspent
dtmStartwork
dblTolerance
intQuantity
lngDistance
sngAverage
strFName
Variant
vnt
vntCheckSum
What the data is used to hold
True or False
Whole numbers from 0–255
Money values, has a fixed decimal point
Date
Large decimal numbers more accurately
Smaller whole numbers –32,768 to 32,767,
Whole numbers that are very large
Decimal number
Any collection of keyboard characters but usually
words
Stores all the above data types but is slow and
wasteful of memory
Bytes
1
8
2
4
4
16
Here is how you would declare a variable
Dim curMoneyspent As Currency
The cur is the abbreviation for currency. This is a naming convention that helps you by letting you know the
type of data that is attached to a particular variable.
Page 3
The Visual Basic opening
screen
Click the Run button to run your application
The Form
window with
our first
project
The
Properties
window
The Toolbox
window
The Code
window
These are some of the most common windows you will see when using Visual Basic
To see other windows select the window you want from the View Menu.
The Form
The blank form is where you will start to design you application. You will place objects on the form, alter their
properties and write the code beneath them.
The Tool Box
The toolbox has controls that you may want to place on your form. These controls can be text boxes, command
buttons, check boxes, option buttons etc. You will learn about these as you progress though the exercises.
Properties Window
This controls how the form and the objects you place on the form will look initially. The code you write can
alter these properties when you run your program.
Project Explorer
This lists all the components such as forms that make up you project. You can click on any item on the project
explorer to display it.
Form Layout
This gives you an initial view of how your form/s will look on the screen.
Page 4
What are Labels?
Programmers use labels to place titles around the form and to label text boxes so users know what to type into
the text box. When you use the Label control, your code can change the label's text so that different messages
can appear when needed.
When you place labels on a form, you'll almost always set the Label control's Name property and type a new
Caption value. In addition, you'll want to change the Font property and possibly the label's color and style.
Below are the most common Label control properties that you'll set as you work with the Label control.
Common label properties.
Property
Description
Alignment
Determines whether the label's caption appears left-justified, centered, or right-justified within
the label's boundaries.
AutoSize
Enlarges the label's size properties, when True, if you assign a caption that is too large to fit in
the current label's boundaries at runtime.
BackColor
Specifies the label's background color. Click the BackColor's palette down arrow to see a list
of colors and click Categorized to see a list of common Windows control colors.
BackStyle
Determines whether the background shows through the label or if the label covers up its
background text, graphics, and color.
BorderStyle
Determines whether a single-line border appears around the label.
Caption
Holds the text that appears on the label.
Enabled
Determines whether the label is active. Often, you'll change the Enabled property at runtime
with code when a label is no longer needed.
Font
Produces a Font dialog box in which you can set the caption's font name, style, and size.
ForeColor
Holds the color of the label's text.
Height
Holds the height of the label's outline in twips.
Left
Holds the number of twips from the label's left edge to the Form window's left edge.
MousePointer
Determines the shape of the mouse cursor when the user moves the mouse over the label.
TabIndex
Specifies the order of the label in the focus order. Although the label cannot receive the direct
focus, the label can be part of the focus order.
ToolTipText
Holds the text that appears as a tooltip at runtime.
Top
Holds the number of twips from the label's top edge to the Form window's top edge.
Visible
Determines whether the label appears or is hidden from the user.
Width
Holds the width of the label in twips.
WordWrap
Determines whether the label expands to fit whatever text appears in the caption.
Page 5
What are Text Boxes?
Text boxes accept user input. Although several other controls accept user input, text boxes are perhaps the
easiest to set up and respond to. In addition, a text box is simple to use, and people see text boxes on Windows
forms all the time.
The table below lists the common properties associated with text boxes. By familiarising yourself with the
properties now, you will be able to more quickly produce applications as you learn more about Visual Basic.
Common text box properties
Property
Description
Alignment
Determines whether the text box's text appears left-justified, centered, or right-justified
within the text box's boundaries.
BackColor
Specifies the text box's background colour. Click the BackColor property's palette down
arrow to see a list of colours and click Categorized to see a list of common Windows control
colours.
BorderStyle
Determines whether a single-line border appears around the text box.
Enabled
Determines whether the text box is active. Often, you'll change the Enabled property at
runtime with code when a text box is no longer needed.
Font
Produces a Font dialog box in which you can set the Text property's font name, style, and
size.
ForeColor
Holds the color of the text box's text.
Height
Holds the height of the text box's outline in twips.
Left
Holds the number of twips from the text box's left edge to the Form window's left edge.
Locked
Determines whether the user can edit the text inside the text box that appears.
MaxLength
Specifies the number of characters the user can type into the text box.
MousePointer
Determines the shape of the mouse cursor when the user moves the mouse over the text box.
MultiLine
Lets the text box hold multiple lines of text or sets the text box to hold only a single line of
text. Add scrollbars if you wish to put text in a multiline text box so your users can scroll
through the text.
PasswordChar
Determines the character that appears in the text box when the user enters a password (keeps
prying eyes from knowing what the user enters into a text box).
ScrollBars
Determines whether scrollbars appear on the edges of a multiline text box.
TabIndex
Specifies the order of the text box in the focus order.
TabStop
Determines whether the text box can receive the focus.
Text
Holds the value of the text inside the text box. The Text property changes at runtime as the
user types text into the text box. If you set an initial Text property value, that value becomes
the default value that appears in the text box when the user first sees the text box.
ToolTipText
Holds the text that appears as a tooltip at runtime.
Top
Holds the number of twips from the text box's top edge to the Form window's top edge.
Visible
Determines whether the text box appears or is hidden from the user.
Width
Holds the width of the text box in twips.
Page 6
What are Form Properties?
Forms have properties that you can and should set when you create an application. Being the background of
your application, the form's properties help set the stage for the rest of the project. The form supports more
property values than the other controls described here, but the list below lists only the most common properties
that you'll need.
New Term: Pixel stands for picture element and represents the smallest addressable graphic dot on your
monitor.
Common form properties.
Property
Description
BackColor
Specifies the form's background color. Click the BackColor's palette down arrow to see a
list of colors and click Categorized to see a list of common Windows control colors.
BorderStyle
Determines how the Form window appears. The BorderStyle property specifies whether
the user can resize the form and also determines the kind of form you wish to display.
Caption
Displays text on the form's title bar at runtime.
ControlBox
Determines whether the form appears with the Control menu icon. The Control menu
appears when your application's user clicks the Control menu icon.
Enabled
Determines whether the form is active. Often, you'll change the Enabled property at
runtime with code when a form is no longer needed. Generally, only multiform
applications, such as MDI applications, need to modify a form's Enabled property.
Font
Produces a Font dialog box in which you can set the text's font name, style, and size.
ForeColor
Holds the color of the form's text.
Height
Holds the height of the form's outline in twips.
Icon
Describes the icon graphic image displayed on the taskbar when the user minimizes the
form.
Left
Holds the number of twips from the form's left edge to the screen's left edge.
MaxButton
Specifies whether a maximize window button appears on the form.
MinButton
Specifies whether a minimize window button appears on the form.
MousePointer
Determines the shape of the mouse cursor when the user moves the mouse over the form.
Moveable
Specifies whether the user can move the form at runtime.
Picture
Determines a graphic image that appears on the form's background at runtime.
ScaleMode
Determines whether the form's measurements appear in twips, pixels (the smallest graphic
dot image possible), inches, centimeters, or other measurements.
ShowInTask bar
Determines whether the form appears on the Windows taskbar.
StartUpPosition
Determines the state (centered or default) of the form at application startup.
Top
Holds the number of twips from the form's top edge to the Form window's top edge.
Visible
Determines whether the form appears or is hidden from the user.
Width
Holds the width of the form in twips.
WindowState
Determines the initial state (minimized, maximized, or normal) in which the window
appears at runtime.
Page 7
Project 1
VB is Fun
To create your first application, follow these steps:
How to start a new project
1. Create a new project by going File/New Project and double-clicking
the Standard EXE icon
2. Change the form's Name property to frmFirst and change its
Caption property to My First Application. The form's
Caption property text appears in the title bar when you run the
application.
How to create a Label
3. Click the Label control and drag a Label on the form
4.
Change the label's
Name property to
lblFirst. Change
the label's Caption
property to VB is
fun.
5. Click the label's Font
property value to
display the Font dialog
box for the label. Set
the font to Arial, the
size to 24 and set
Bold property.
6. Change the fore
colour to Orange,
or any colour you
choose, and change
the label's
Alignment property to 2-Center.
7. Change the label's BorderStyle property to 1-FixedSingle.
This property adds a single-line 3D border around the label. Change the
shape of the label to fit the text.
How to create a Command Button
8. Add a Command button, but to do so, double-click the command button tool on the Toolbox window.
The command button appears in the middle of the form and you can leave it where it is.
9. Change the command button's Name property to cmdExit.
10. Change the command button's Caption property to Exit. Watch the command button as you type the
Caption property text. The command button's caption becomes the text you type.
11. The command button will be used to exit the program. When the user clicks the command button, your
application should end. When a user clicks a command button a Click event occurs. Therefore, to
respond to this event, you must write an event procedure for the command button. Double-click the form's
command button and Visual Basic instantly opens the Code window and displays the following wrapper
lines for the command button's Click event procedure:
Page 8
How to write code
The name of the procedure, cmdExit_Click(), describes both the control and the event being
processed by the code you only need to fill in the body. Type End for the one-word body of the event
procedure and close the Code window. End tells Visual Basic to end the running application. Therefore,
the application will end when the user clicks the command button.
Press Tab, to insert a space then type End
Press the Run button to run the program and watch your creation appear.
We are going to make a button that will change the words VB is Fun, in
the Label to I love computing.
1. Create another Command Button and set the Name to Cmdchange,
and the Caption to Computing.
2. Double click on the button to open the Code window. Type in the
following:
Lblfirst.Caption = "I love Computing"
Remember earlier we set the properties for the label caption as VB is fun.
This code says for the caption field of Lblfirst put the words I love
computing.
The words will be too big for the Label window, so we
need to make the font size smaller as well. So lets set
the height of the label to 1400 by adding in the
following:
Lblfirst.Height = 1300
We need to make the Label window wider to fit the
words so also add:
Lblfirst.Width = 3000
Run the program by clicking on the Run
button and see if it works.
Exercise
Make another Command button to return
the Label to the original VB is Fun
settings.
Page 9
Saving a Visual Basic Program
1
Click Save Project
on the tool bar.
Click Create New
Folder
3
2
4
Type a name for the new
folder eg Add and
Average
Double click on the new
folder to open it
Check that you have a
new named empty folder
to save your project in.
5
Click the Save
button
Type in a new name
for the project
the
6
Click the Save
button
7
You may need to save several files depending on the number of forms used and the
objects such as pictures placed on the form.
To save your work again just click the Save button.
Page 10
Project
The Personal Computer
Getting Started
1) Start Visual Basic
2) Double click Standard
EXE
This is how your
completed form
will look
3) Click on the form and
in the Properties window in the Name
field change the name of the form to
frmComputer, then in the Caption field
change the name of the Caption to PC
Parts.
How to create a Label
4) Drag a label onto the form to make the title
Personal Computer. In the properties
window change the Name to Lbl1
5) In the Caption field type in The Personal Computer
6) Click in the Font field within the Properties window to
display the Font dialog box. Choose Arial Bold 14pt.
7) Click on the Alignment field and choose Center
How to place graphic images on the form
8) Select the Image tool from the toolbox and position it in
the centre of the form window in the same way you
positioned the label, by dragging it from top left corner
to the bottom right corner to form a rectangular box.
9) Make sure the image frame is selected (handles showing)
10) In the Properties window click the Picture field, an ellipsis (–) will appear, click on the ellipsis to
bring up a File Load dialog box. Load the image of a computer, called _____________
11) Repeat the above steps to add the pointer image called _____________
How to add a command button
1) Select the Command tool from the tool box and
position it at the bottom of the form.
Name cmdMonitor
Caption Monitor
Font
12pt
ToolTipText
Point at Monitor
2) In the properties window change the following
fields to:
How to use Copy to add two more command buttons
1) Select the command button you have already made and copy it.
(Menu bar  Edit  Copy then Menu bar  Edit  Paste, or alternatively CTRL C then
CTRL V
2) To the dialog box that asks, “Do you want a Control Array”, click No
Page 11
3) Repeat this procedure to make a third button
4) Select the second button and change its properties to
Name
cmdKeyboard
Caption
Keyboard
ToolTipText Point at
Keyboard
5) Select the third button and change its properties to
Name
cmdMouse
Caption
Mouse
ToolTipText Point at Mouse
6) You are going to record the position of the pointer when it points at the Monitor, Keyboard
and Mouse. To do this move the pointer to the position you want then record the two values,
Left and Top from the Properties window. Use the table below to record the positions.
Pointer pointing at
Monitor
Keyboard
Mouse
Left
Top
How to write code behind the buttons to move the pointer when you click any of
the three buttons.
1) Double click the Monitor command button on the form, then enter the position of the pointer as
shown below into the Private Sub cmdMonitor_Click()
Private Sub cmdMonitor_Click()
imgPointer.Left = 2160
imgPointer.Top = 2040
End Sub
Hint: To display the form
double click Form1 in the
Explorer window
.
2) Double click the Keyboard command button on the form, then enter the position of the pointer as
shown below into the Private Sub cmdKeyboard_Click()
Private Sub cmdKeyboard_Click()
imgPointer.Left =
imgPointer.Top =
End Sub
3) Double click the Mouse command button on the form, then enter the position of the pointer as
shown below into the Private Sub cmdMouse_Click()
Private Sub cmdMouse_Click()
imgPointer.Left =
imgPointer.Top =
End Sub
How to run your program to see if it all works
1) Click the Start button on the main (top) toolbar
Page 12
2) Click each of your command buttons in turn (Monitor, Keyboard, Mouse) and the graphic pointer
image should move to point at each part.
3) Save your work by selecting Save Project As from the file menu. Name the file PC Parts.
Structure Diagrams
Background
In our programs we write lines of code to tell the computer what to do one step at a time. The lines must be
written in the correct order and the computer will carry out each one after the other. The code is said to be
sequential, i.e. the program is a sequence of steps.
When programs become more complicated we need to have a way of planning and designing our code so that
the correct steps will be coded in the correct sequence. Structure diagrams are a tool to aid program design.
Structure diagrams are made up of boxes which describe a step in the program. These steps might be large or
small, large ones can be broken down gradually into smaller ones. We may need to have several levels to a
structure diagram.
An operation A is shown as a sequence of steps in the diagrams below.
What Fig (a) tells us is that A is really done by first doing B, then C and finally D. The chart is read from the
top down and from left to right. Fig (b) is diagram with another level in which step B is done by doing steps C
and D.
Fig (a)
B
Fig (b)
A
C
D
A
B
E
C
F
D
Sequence
This is where one step is done after the other. Figs a, b and C are all simple sequences.
The diagram Fig (c) below shows the sequence of steps you carry out when you log on to the network.
Logging
on
Fig (c)
Enter User
ID
Type in ID
Enter
Password
Press Tab
Exercises
Draw Structure Diagrams for the following situations:
1. Saving a newly created file on a floppy disc
2. Cleaning your teeth.
Page 13
Type
Password
Press Enter
3. Starting the car.
4. Changing a car tyre.
5. Recording a TV program on a Video Tape
Project
Simple Addition
Below is a structure diagram showing the steps you will take to add two numbers using VB.
Add Two
numbers
Get the first
number
Get the second
number
Add the two
numbers
Display the
result
sngNum1 
val(txtNum1.text)
sngNum2 
val(txtNum2.text)
sngSum 
sngNum1 + sngNum2
lblSum.caption
sngSum
When you write a computer program you have to get data into the computer (Input), process it and then display
the results (output). A text box is just one object that can be placed on a form so that you can key in data.
Getting Started
1. Start Visual Basic
2. Double click Standard EXE
3. Enlarge the form by dragging its bottom right corner
handle so that it size is about width 3500 height
26400
4. In the Properties window double click the Name field
and change the name of the form to frmAdder, then
double click the Caption field and change the name of
the Caption to Adder.
How to create a Label
1. Select the label tool from the tool box and position it at the top of the form, by dragging from the
top left to the bottom right corner to form a rectangular box.
5. With the label selected double click in the Caption field of the Properties window and type in the
new caption ‘Adder’
6. Click on the Font field within the Properties window to display an ellipses (–)
7. Click on the ellipsis to display the Font dialog box
8. Choose 18 pt from the Font dialog box
9. Click on the Alignment field in the Properties window and from the menu choose Center
10. Create another label to hold the answer
11. Set the following properties
Name
Border Style
Caption
Font
lblSum
Fixed single
Remove any text to make it blank
12 pt
Page 14
How to select the TextBox tool from the tool box.
1. Create a text box and set the font property to 12pt
2. Copy this text box to make two text boxes. Both will now have the same font size.
3. Position the text boxes as shown in the example above, remove the text from the Text Property
and name the boxes:
Name
txtNum1
txtNum2
4. Select the Command tool from the tool box.
5. Create a command button and set the font property to 12pt
6. Copy this button twice and name the buttons:
Name
cmdAdd
cmdClear
Caption
&Add
&Clear
7. Arrange the buttons as shown in the form above.
Private Sub cmdAdd_Click()
Dim sngNumone As Single, sngNumtwo As Single, sngSum As Single
‘declares three variables as single precision (sng)
sngNumone = Val(txtNum1.text)
‘converts text to a number and assigns it to sngNumone
sngNumtwo = Val(txtNum2.text)
‘converts text to a number and assigns it to sngNumtwo
sngSum = sngNum1 + sngNum2
‘adds sngNum1 to sngNum2 and assigns this to sgnSum
lblSum.caption = sngSum
End Sub
Private Sub lblClear_Click()
TxtNum1.text = ""
TxtNum2.text = ""
LblSum.caption = ""
End Sub
‘assigns an empty string to txtNum1
‘assigns an empty string to txtNum2
‘assigns an empty string to txtNum3
The Val function
Converts a string (text) to a number. If the text can not be recognised as a number then the value will be set to
zero. If val is not used and no number is entered an error will occur.
Dim (Dimension)
Declares variables, in this case as single precision numbers. This means they can be decimal numbers taking 4
bytes to store them. This is OK as long as you don’t need to use extremely large numbers.
Remarks
Any text that starts with a ‘ single quotation mark is ignored. This is part of the documentation that you add to
your program to remind you what a piece of code does.
Naming Conventions
Variables are prefixed with the abbreviation for their data type eg. sng for a single precision number.
Giving your command button a key shortcut.
In the applications you have used this year you will notice that all command buttons have an underlined letter.
Eg Calculate. In this example the C of calculate is underlined. Pressing the key combination Alt C will have
the same effect as clicking the Calculate button.
To add this feature simply prefix the word calculate with the "&" ampersand character eg. &Calculate
Tpo
Page 15
Converting Celsius to Fahrenheit
The structure diagram below outlines the steps you will carry out to convert a temperature entered in degrees
Celsius to degrees Fahrenheit.
Convert Celsius
to Fahrenheit
Get degrees
Celsius
Calculate degrees
Fahrenheit
Display
Fahrenheit
sngCelsius
Val(txtCelsius.text
sngFahrenheit
sngCelsius * 9/5 + 32
lblFahrenheit.caption
sngFahrenheit
This exercise requires three static labels, one label to display the temperature in Fahrenheit, one text box for
input and one command button.
1. Create the form as shown below
2. Add the code to the Convert command button
Form properties
Name
FrmFahrenheit
Caption
Find Degrees Fahrenheit
Text box properties
Name
txtCelsius
Caption
Nothing
Label properties
Name
lblFahrenheit
Caption
Nothing
Border
Fixed single
Command button properties
Name
cmdConvert
Caption
&Convert
The Code
Double Click on the Convert button and then enter the code below:
Private Sub cmdConvert_Click()
Dim sngCelsius As Single
Dim sngFahrenheit As Single
sngCelsius = Val(txtCelsius.Text)
sngFahrenheit = sngCelsius * 9 / 5 + 32
lblFahrenheit.Caption = sngFahrenheit
End Sub
'subroutine that responds to clicking the button cmdConvert
'Declares a decimal number variable called sngCelsius
'Declares a decimal number variable called sngFahrenheit
'Converts text into a number
'Calculates the value for sngFahrenheit
'Displays the value of sngFahrenheit in the label caption.
Making the conversion program respond to the Enter key rather than the
command button
In this example we show you how to Respond to the Enter key
being pressed rather than having to click the Convert button.
The KeyPress Event.
This occurs each time you press any key on the keyboard,
however we only want to respond when the Enter Key is
pressed. This is easily done as the Enter key returns the ASCII
code 13 when pressed, therefore our program must do the
calculation only IF KeyAscii = 13 (Enter Key)
Page 16
Press Enter
When you press the Enter key in a text box it beeps. To prevent this happening KeyAscii is set to zero.
1. Modify the code to that shown below
2. Delete the cmdConvert button
Private Sub txtCelsius_KeyPress(KeyAscii As Integer)
If KeyAscii = 13 Then
KeyAscii = 0
Dim sngCelsius As Single
Dim sngFahrenheit As Single
sngCelsius = Val(txtCelsius.Text)
sngFahrenheit = sngCelsius * 9 / 5 + 32
lblFahrenheit.Caption = sngFahrenheit
End If
End Sub
'Responds to keypresses returning the keys pressed
'Routine below is only done if the Enter (key 13) is pressed
'Stops the beep when Enter is pressed
'Declares sngCelsius as Single
'Declares sngFahrenheit as Single
'Converts text to a number
'Calculates a value for sngFahrenheit
'Displays sngFahrenheit in the label lblFahrenheit
'End of the If decision
'End of the subroutine
Making the program more versatile
Now we will make is possible to enter either Celsius or Fahrenheit with keypresses. This will require two
routines, one attached to each text box.
Convert Celsius
to Fahrenheit
Get degrees
Celsius
Calculate degrees
Fahrenheit
Display
Fahrenheit
sngCelsius
Val(txtCelsius.text
sngFahrenheit
sngCelsius * 9/5 + 32
txtFahrenheit.text
sngFahrenheit
Convert Fahrenheit
to Celsius
Get degrees
Fahrenheit
Calculate
degrees Celsius
Display
Celsius
sngCelsius
Val(txtFahrenheit.text
sngCelsius 
(sngFahrenheit - 32) * 5/9
txtCelsius.text
sngCelsius
The two routines shown above are attached to the two text boxes
It is now possible to type into either text box and when you press enter the conversion will occur and appear in
the other text box.
You will need to:
1. Delete the label used for displaying the temperature in Fahrenheit
2. Add a text box called txtFahrenheit
3. Enter the new code below
Private Sub txtFahrenheit_KeyPress(KeyAscii As Integer)
'Responds to keypresses returning the keys pressed
If KeyAscii = 13 Then
'Routine is only done if the Enter (key 13) is pressed
KeyAscii = 0
'Stops the beep when Enter is pressed
Dim sngCelsius As Single
'Declares sngCelsius as Single
Dim sngFahrenheit As Single
'Declares sngFahrenheit as Single
sngFahrenheit = Val(txtFahrenheit.Text)
'Converts text to a number
sngCelsius = (sngFahrenheit - 32) * 5 / 9
'Calculates sngCelsius
txtCelsius.Text = sngCelsius
'Displays sngCelsius in txtCelsius text box
Page 17
End If
End Sub
Private Sub txtCelsius_KeyPress(KeyAscii As Integer)
If KeyAscii = 13 Then
KeyAscii = 0
Dim sngCelsius As Single
'Ends block If
'Ends subroutine
'Responds to keypresses returning keys pressed
'Routine is only done if the Enter (key 13) is pressed
'Stops the beep when Enter is pressed
'Declares sngCelsius as Single
Dim sngFahrenheit As Single
sngCelsius = Val(txtCelsius.Text)
sngFahrenheit = sngCelsius * 9 / 5 + 32
txtFahrenheit.Text = sngFahrenheit
End If
End Sub
'Declares sngFahrenheit as Single
'Converts text to a number
'Calculates sngFahrenheit
'Displays sngFahrenheit in txtFahrenheit text box
'Ends block If
'Ends subroutine
Formatting numbers
The most often required format is currency which adds leading "$" dollar sign and formats to two decimal
places.
Examples:
lbltotal.caption = Format(45,"currency")
$45.00
or
curSum = 45
lblTotal.caption = Format(curSum,"currency")
Exercises
Write three programs to convert $NZ to $Aus: For each
program draw a structure diagram.
1. Write a program that uses a text box for input, a label for
output and a command button to
Calculation is
calculate the result which is to be
attached to the click
$Au. The conversion rate is $1
event event.
NZ = $0.70 AU
2. Write another program similar to
the one above except that it uses a
keypress rather than a command
button.
$NZ input
here
$AU is
displayed
here
Calculation is
attached to the
keypress event
3. Modify program three so that it converts both ways. ie. $NZ
to $Aus and $Aus to $NZ in a similar way to the
temperature converter. It must be possible to type into either
text box and have the program display the conversion in the
other text box.
Press Enter
Here
Or Press Enter
Here
Extension exercise
Create another text box in order that the conversion rate can be entered rather than having it fixed at 7/10 (.7)
Page 18
Write a program to calculate the cost of petrol for a trip
Start by:
1. drawing up a structure diagram
2. naming each object on the form. Use the table below:
Complete the table of named objects that you will need for the form to work. Some of this has been done for
you.
Object Name
Caption/Text
Variable Name
Variable datatype
Form
Name
frm
Caption
Text boxes
Cost per litre
txt
cur
currency
Distance Travelled (km)
txt
sng
single
Petrol used (km)
txt
sng
single
Labels
Total petrol cost
lbl
cur
currency
Cost per kilometre
lbl
cur
currency
Command buttons
Calculate
cmd
&
Reset
cmd
&
3. Create the objects as shown on the form below,
name them and enter their properties.
4. Write the code to that goes behind the two
buttons. The Reset button is to clear all the text
boxes and labels that hold the results.
eg.
txtCostPerLitre.text = ""
lblTotalCost.Caption = ""
Selections and Decisions
So far all the programs we have written have been sequential steps which are done is in order 12, 3… etc.
IF statements make this possible.
A simple decision may be, "Can I Vote?". This will be true if I am 18 or over. Below is a decision tree and a
structure diagram to show how this decision can be represented graphically. The decision tree only shows the
decision logic whilst the structure diagram shows the complete program.
Structure
Diagram
Can I Vote?
Decision Tree
Is intAge >= 18
Yes
No
Can Vote
Can't Vote
Get intAge
Is intAge
>=18
Yes
Display "Can
Vote"
Page 19
No
Display "Can't
Vote"
1. Create the form opposite with the following named objects
Type
Form
Text box
Label
Label
Name
FrmAge
txtAge
LblDecision
Caption/Text
Can I vote?
None
Enter Age
None
Type in
age and
press Enter
2. Enter the code below under the txtAge text box.
Private Sub txtAge_KeyPress(KeyAscii As Integer)
If KeyAscii = 13 Then
Dim intAge As Integer
intAge = Val(txtAge.Text)
If intAge >= 18 Then
lblDecision.Caption = "Yes you can vote"
Else
lblDecision.Caption = "No you can't vote"
End If
End If
End Sub
'Only do if the key pressed is 13 "Enter"
'Declare intAge as an integer (whole number)
'Convert txtAge to a number
'Check whether intAge is 18 or over
'Response when intAge is 18 or over
'Response when intAge is under 18
'End of second IF
'End of first IF
'End of subroutine
Loops
Loops make it possible to repeat a section of code a number of times. This is used for doing calculations,
searching and sorting lists etc.
Start of Loop
Code
End of loop
For… Next loop
This is a loop with an in-built counter. The syntax is:
For counter = start To end Step increment
Code here
Next counter
The counter automatically increases or decreases by the value of the increment each time around the loop.
The step increment can be omitted, in which case the step will be one.
Here some examples of a For…Next loop.
Positive step of one from a given number
For intCounter = 1 To 6
PicDisplay.Print intCounter;
Next intCounter
Displays 1 2 3 4 5 6
Negative step of minus one from a given number
For intCounter = 6 To 1 Step –1
PicDisplay.Print intCounter;
Next intCounter
Page 20
Displays 6 5 4 3 2 1
Positive step of plus two from a given number
For intCounter = 0 To 10 Step 2
PicDisplay.Print intCounter;
Next intCounter
Displays 0 2 4 6 8 10
Project … Exploring loops
The structure diagram below shows a simple program to demonstrate how a For…Next loop works
Loop and display C ounter
values.
Symbol
for a loop
Dimension v ariables
intC ounter as Integer
intStart as I nt eger
intFinish as Integer
intStep as Integer
For intCounter  int Start To
intFinish Step intStep
Get Values
intStart Val(txtStart.Text)
intFinish Val(txtFinish.Text )
intC ounter Val(txtCounter.Text )
picDisplay .Print
intC ounter
Text box
Named
txtStep
Text box
Named
txtStart
Picture box
named
picDisplay
Text box
Named
txtFinish
1.
2.
Start button
named
cmdStart
Create the form shown above and name all the objects as shown.
Enter the code attached to the Start button as shown below.
Option Explicit
Private Sub cmdStart_Click()
Dim intStart As Integer
Dim intFinish As Integer
Dim intCounter As Integer
'dimension the starting number
'dimension the finishing number
'dimension the counter
Page 21
Dim intStep As Integer
picOutput.Cls
intStart = Val(txtStart.Text)
intFinish = Val(txtFinish.Text)
intStep = Val(txtStep.Text)
For intCounter = intStart To intFinish Step intStep
picDisplay.Print intCounter;
Next intCounter
End Sub
3.
'dimension the step value
'clear the picture box
'convert text to number
'convert text to number
'convert text to number
'start of loop
'code repeated in the loop
'finish of loop
Run the program and enter the values in the table below. Write in the Output column the output you
get when each set of values is entered.
Start
Finish
Step
1
6
6
1
-1
0
10
2
12
0
-2
Output
Problems
a)
b)
c)
d)
e)
f)
g)
Enter two integers and add all integers from the first integer to the second. If 1 and 6 were
entered the calculation would be 1 + 2 + 3 + 4 + 5 + 6 and the answer would be 21.
Enter two integers and add all even integers from the first integer to the second. If 2 and 10
were entered the calculation would be 2 + 4 + 6 + 8 + 10 and the answer would be 30.
Find the sum of 1 + ½ + 1/3 + ¼ … 1/100
Produce a table to display the conversion of NZ dollars $ to English pounds £ for 1 to 10
dollars. Have an input box to type in the exchange rate.
Display a times table from 1 to 10. Have an input box to enter the table you want printed.
Convert Celsius to Fahrenheit as a table ranging from 0 to 40 degrees Celsius in steps of 5.
Fahrenheit = Celsius x 9/5 + 32
Create a depreciation calculator to calculate the value of any item after a given period of years.
Eg You buy a car for $16,000 and it depreciates at 9.5% each year, then how much will it be
worth after 12 years. An example of the layout is shown below.
The code for the Calculate button has been done for you. You are to
 Create the form and objects shown below
 Draw a structure diagram for the Clear button
 Write the code for each event (Calculate, Clear, Exit)
Page 22
Below is a structure diagram for the Calculate button only.
Calculat e
Depreciat ion
(cmdCalculat e)
Dimension Variables
Dim sngInit ialValue As Single
Dim sngDepreciat ion As Single
Dim int Years As Int eger
int YearCount As Int eger
Loop
For int YearCount  1
T o int Years
Get Values
sngInit ialValue = Val(t xt Init ialValue.T ext )
sngDepreciat ion =
Val(t xt Depreciat ion.T ext )
int Years = Val(t xt Years.T ext )
Display New Value
lblFinalValue.Capt ion =
Format (sngInit ialValue, "currency")
sngInit ialValue  sngInit ialValue sngInit ialValue * sngDepreciat ion / 100
Strings – String Functions
The string data type is any text, which can include any keyboard character.
String variables are declared like this: Dim strWord as String where strWord is the variable name.
Len
Len returns the length of the string in number of characters. See the example below.
strName = “Hagley Community College”
intLength = Len(strName)
intLength’s value would be 24 as this is the number of characters including spaces in the name “Hagley
Community College”
Right
Right returns a specified number of characters from the right side of a string
strName = “Hagley Community College”
strRightSide = Right(strName, 7)
The variable strRightSide would be “College” as College is the 7 rightmost characters.
Left
Left returns a specified number of characters from the left side of a string
strName = “Hagley Community College”
strLeftSide = Left(strName, 6)
The variable strLeftSide would be “Hagley” as Hagley is the 6 leftmost characters.
Mid
Mid returns a specified number of characters from a string starting at a given start position and the
specified length.
strName =”Hagley Community College”
strMiddle = Mid(strName, 7, 9)
The variable strMiddle would be “Community” as Community is 7 characters from the start of the string
and 9 characters in length.
Note: With the Mid function you can remove the last parameter.
strMiddle = Mid(strName,7)
The variable strMiddle would now be “Community College” as no length value has been entered.
Page 23
InStr
Instr searches for a smaller string within a larger string.
strName = ”Hagley Community College”
strShort = ”Community”
intPosition = InStr(1,strName, strShort,1)
The value of intPosition would be 8 as this is the start position of the shorter string “College “ in the
larger string “Hagley Community College”
If the strShort is not found within strName then the value returned will be zero.
Note
The first parameter 1, is the position in the string to start searching from.
The fourth parameter,1 results in a noncase-sensitive search.
UCase
UCase converts all lower case letters in the string to upper case.
strName = “Hagley Community College”
strName = Ucase(strName)
The string variable strName would now be equal to “HAGLEY COMMUNITY COLLEGE”
LCase
LCase converts all upper case letters in a string to lower case.
strName = “HAGLEY COMMUNITY COLLEGE”
strName =LCase(strName)
The string variable strName would now be equal to “hagley community college”
Simple programs to illustrate string functions
Project …Reversing a string
This program uses the following string functions:

Len

Mid
A For… Next loop is used with Mid function to reverse the
letters in a string. In this example a single letter is extracted at
a time starting with the last letter in the word. Letters are
joined together to make a word using the & (joining
operator).
The code is attached to a Keypress event.
The Structure Diagram
Reverse a Word
Dimension Variables
Dim strWord as String
Dim strReversedWord as string
Dim intCounter as integer
Dim intLength as integer
Get a word
strReversedWord
 ""
intLength 
Len(strWord)
For intCounter 
intLength To 1 Step -1
strReversedWord  strReversedWord &
Mid(strWord,intCounter,1)
strWord  txtWord.text
Page 24
lblDisplay.caption
strReversedWord

The Code
Option Explicit
Private Sub txtWord_KeyPress(KeyAscii As Integer)
If KeyAscii = 13 Then
'only continue if the enter key (13) is pressed
KeyAscii = 0
'stop the beep when enter is pressed
Dim strWord As String
'variable for word entered
Dim strReversedWord As String
'variable for the reversed word
Dim intCounter As Integer
'variable for loop counter
Dim intLength As Integer
'variable for length of word
strWord = txtWord.Text
'get text from text box
strReversedWord = ""
'set to null string
intLength = Len(strWord)
'find the lenght of the word
For intCounter = intLength To 1 Step -1
'start of loop
strReversedWord = strReversedWord & Mid(strWord, intCounter, 1)
Next intCounter 'end of loop
lblDisplay.Caption = strReversedWord
'display the reversed word in the label caption.
txtWord.SelStart = 0
'start of highlighted area
txtWord.SelLength = intLength
'length of highlighted area
End If
End Sub
Page 25
Project …Joining Strings – Concatenation
This program uses the following functions

Left
Joining of strings is done with the & joining operator.
This program illustrates how it is possible to split and
recombine strings.
The Structure Diagram
Enter and combine title initial
and Surname
Dimension Variables
Dim strTitle as String
Dim strSurname as String
Dim strFirstName as String
Dim strCombined as String
Get title and names
strTitle = txtTitle.text
strSurname = txtSurname.text
Combine title and
names
strCombined = strTitle & " " &
Left(strFirstName,1) & " " & strSurname
Code
Option Explicit
Private Sub cmdCombine_Click()
Dim strTitle, strSurname, strFirstName, strCombined As String
strTitle = txtTitle.Text
strFirstName = txtFirstName.Text
strSurname = txtSurname.Text
strCombined = strTitle & " " & Left(strFirstName, 1) & " " & strSurname
lblCombined.Caption = strCombined
End Sub
Page 26
lblCombined.Caption =
strCombined
Project … Splitting Strings
This program uses the following functions.

Instr

Mid
It is more complex than the program to join strings.
InStr is used to return the position of the spaces in
the string.
Mid is used to extract the section of name up to the
space. For the last section of the string Mid is used
without the last parameter thus only the start point is
given for the string.
This program will only work if there is one space
between each word.
A control array is used to display the split name.
Structure Diagram
Spli t Name into
Components
Declare Variables
Dim
Dim
Dim
Dim
strFullName as String
strN ame as String
int Space as Integer
int Next Space as Integer
Get Name
strFullName  txtFullName.text
int Next Space  InStr(intSpace,strFullname," ",1)
int Space  1
strN ame  Mid(strFullName, int Space)
lblName(2).Caption 
strN ame
For intC ounter  0 to 1
strN ame  Mid(FullName, intSpace,int Next Space - intSpace)
lblName(intC ounter). Capt ion  st rName
Code
Option Explicit
Private Sub txtFullName_KeyPress(KeyAscii As Integer)
If KeyAscii = 13 Then
KeyAscii = 0
Dim strFullName, strName As String
Dim intSpace, intNextSpace, intCounter As Integer
strFullName = txtFullName.Text
intSpace = 1
For intCounter = 0 To 1
intNextSpace = InStr(intSpace, strFullName, " ", 1)
strName = Mid(strFullName, intSpace, intNextSpace - intSpace)
lblName(intCounter).Caption = strName
intSpace = intNextSpace + 1
Next intCounter
strName = Mid(strFullName, intSpace)
lblName(2).Caption = strName
txtFullName.SelStart = 0
txtFullName.SelLength = Len(strFullName)
End If
End Sub
Page 27
int Space  intSpace +1
Project …Word Counter
This program uses the following function:

InStr
This program uses a Do…Loop to find all the occurrences of
a word in a sentence or paragraph. The loop repeats until no
more occurrences of the word are found, and this is when
intStart = 0.
Structure Diagram
Co un t wo rds i n a
sen tence
Declare Variables
Init ialise Variables
int Start 
InSt r(int Start ,
strSentence, strWord,
1)
Display Number
Get Sent ence and Word
Do Until inSt art  0
Dim intStart as I nt eger
Dim intWordCount As I nt eger
Dim strSentence As String
strSentence 
txtSentence. Text
lblWordcount .Caption
 int WordCount
End If
intWordCount  0
intStart  1
int WordCount 
intWordCount + 1
strWord  txtWord.Text
int Start  InStr(intSt art
+ 1, strSent ence,
strWord, 1)
Code
Option Explicit
Private Sub txtWord_KeyPress(KeyAscii As Integer)
If KeyAscii = 13 Then
KeyAscii = 0
Dim intStart, intWordCount As Integer
Dim strSentence As String
Dim strWord As String
strSentence = txtSentence.Text
strWord = txtWord.Text
intStart = 1
intWordCount = 0
intStart = InStr(intStart, strSentence, strWord, 1)
Do Until intStart = 0
intWordCount = intWordCount + 1
intStart = InStr(intStart + 1, strSentence, strWord, 1)
Loop
lblWordcount.Caption = intWordCount
End If
End Sub
Page 28
‘stop beep
‘dimension all integer variables
‘dimension string variables
‘get sentence form text box
‘get word from text box
‘set start search position to 1
‘set words counted to zero
‘find the position of the first occurrence
‘loop until no more words are found
‘check for subsequent words
‘finish of loop
‘display the number of words found
Visual Basic – Arrays
An Array is a special type of variable that holds more than a single item of data. Before you can use an
array you have to tell the computer how large the array (list) is to be. This is done in a Dim statement.
e.g. Dim Names(100) would create an array to hold Names(0) to Names(100), in other words this array
would hold 101 names. Note that there is a zero element to an array, hence Dim Names(100) will hold
101 names not 100 as you may expect. Arrays, like other variables can be of any of the data types such as
Integer, Single, String… etc.
Suppose that you wish to store 5 names without using an array. You will need to declare 5 variables. e.g.
Dim NameOne as string
Dim NameTwo as string
Dim NameThree as string
Dim NameFour as string
Dim NameFive as string
To input the names you will need 5 text boxes as well as 5 variables and the code will be:
strNameOne = txtNameOne.Text
strNameTwo = txtNameTwo.Text
strNameThree = txtNameThree.Text
strNameFour = txtNameFour.Text
strNameFive = txtNameFive.Text
Now imagine how clumsy it would be if you need to add a hundred or more names to a hundred variables.
To do the same task with an array the code is:
Dim strNames(4) as String
Dim intCounter as integer
Set intCounter to –1 in the Form Load area and then increment(increase) intCounter by 1 and assign the
name to the variable each time you increase the counter.
IntCounter = intCounter + 1
StrNames(intCounter) = txtNames.Text
Here is some code that could be used to enter up to 101 names to an array variable.
General Area
Dim IntCounter as Integer
Dim strNames(100) as String
Here is the way the array
works
Names(100)
Private Sub cmdStart_Click()
IntCounter = -1
End Sub




0
1
Private Sub txtEnter_Keypress(KeyAscii as Integer)
2
If KeyAscii = 13 And txtEnter.Text <> “” Then
3
IntCounter = intCounter + 1
4
strNames(intCounter) = txtEnter.Text
5
txt.Enter.SetFocus
6
txtEnter.SelStart = 0
7
txtEnter.SelLength = Len(txtEnter.Text)
8
End If
…
End Sub
When the data is in an array it can be.100
Printed out
Printed out in Reverse order
Searched for matches
Sorted into Alphabetic (Ascending or Descending order)
Page 29
Fred
Mary
Lee
Tania
Jack
Tahu
…
Printing out data from an array
To make it simple the contents of the array are printed out to a picture box. The routine uses a For…Next
loop where the start value is 0 and the finish value is the number of names in the array which is stored in
the global variable called intCounter. A Step value is not given as the default step is + 1.
Here is the routine to print out an array.
Private Sub cmdForward_Click()
Dim intIndex As Integer
picDisplay.Cls
For intIndex = 0 To intCounter
picDisplay.Print intIndex; " ";
strNames(intIndex)
Next intIndex
End Sub
Disp layi ng
an array
For intIndex  0 To
intC ounter
picDisplay .Print
intI ndex; " ";
strNames(intI ndex)
Printing the data in reverse order
0
1
2
3
4
5
6
7
8
9
10
Fred
Charlie
Zane
Mary
Paul
Tahu
Mohammad
Lee
Tania
Tina
Rick
This Procedure is almost the same as the procedure to print out the names in a forward direction, the only
differences are the start and finish values are reversed and a negative Step value of –1 is added.
Private Sub cmdReverse_Click()
Only this line of code differs
Dim intIndex As Integer
from the Sub cmdForward
picDisplay.Cls
For intIndex = intCounter To 0 Step -1
picDisplay.Print intIndex; " "; strNames(intIndex)
Next intIndex
End Sub
Carrying out a simple sequential search
Searching is done by typing in a search string and then comparing the search string with each element in
the array and printing it out if it matches.
The Left function is used so that a “Begins with” search is implemented.
A For…Next loop is used to step through each element of the array to check if it matches the search
string.
Searching
strSearchString 
txtEnter.Text
intLength 
Len(strSearchString)
intIndex  -1
For intIndex 
0 To intCounter
Is
strSearchString =
Left(strNames(intIndex),
intLength)
Yes
picDisplay.Print
strNames(intIndex)
Private Sub cmdSearch_Click()
Dim intIndex As Integer
Dim intLength As Integer
Page 30
End Sub
Dim strSearchString As String
Len Finds the
strSearchString = txtEnter.Text
length of the
intLength = Len(strSearchString)
search string
intIndex = -1
picDisplay.Cls
For intIndex = 0 To intCounter
If strSearchString = Left(strNames(intIndex), intLength) Then
picDisplay.Print strNames(intIndex)
End If
Next intIndex
The search string
is looked for in
each element of
the array.
A more complex search could be setup using the string functions, Left, Right and Instr.
Sorting data in an array
There are many ways of sorting data in an array. The bubble sort is not the most efficient but is by far the
simplest to follow.
Sorting is done by:
1. Comparing the first element in the array with each other element and swapping if first is greater than
the second.
2. Comparing the second element in the array with each other element and swapping if it is greater than
the other
3. This is repeated until the second to last element has been compared with the last element.
Sorting is done using two nested For…Next loops. The Pseudocode below shows simply how this is
done.
For intInner = 0 To intCounter –1
For intOuter = intInner + 1 To intCounter
Compare the strNames(intInner) with strNames(intOuter)
If StrNames(intInner) > StrNames(intOuter) Then Swap them
Next intInner
Next intOuter
Visual Basic is able to make comparisons between strings using simple relational operators.
Eg strNames(0) > strNames(1) will compare the strings using the value of the Ascii code that makes up
each letter of the word.
Note that upper case letters all have smaller Ascii Codes than lower case letters. An ascending sort will
put Upper case letters first.
To carry out a case independent sort the function UCase or LCase can be used.
The diagram below shows how the comparisons are made for the First 3 passes of the Outer loop.
StrNames(0) is compared with strNames(1) and swapped if the first name is larger than the second.
strNames(0) is compared with strNames(2)
strNames(0) is compared with strNames(3)
strNames(0) is compared with strNames(5)
strNames(0) is compared with strNames(6)
strNames(0) is compared with strNames(7)
strNames(0) is compared with strNames(8)
strNames(0) is compared with strNames(9)
strNames(0) is compared with strNames(10)
strNames(1) is compared with strNames(2)
strNames(1) is compared with strNames(3)
strNames(1) is compared with strNames(4)
…
strNames(9) is compared with strNames(10)
Page 31
Diagram to show Sorting
Third Pass
Second Pass
0
1
2
3
4
5
6
7
8
9
10
First
Pass
Right is a structure diagram for a sort
routine.
Zane
Charlie
Mary
Jane
Paul
Fred
Andrea
Tahu
Rick
Andrew
Michael
BubbleSort
For intOuter  0 To
intCounter - 1
For intInner  intOuter
+ 1 To intCounter
Is
strNames(intOuter) >
strNames(intInner)
Yes
strTemp 
strNames(intInner)
strNames(intInner) 
strNames(intOuter)
strNames(intOuter) 
strTemp
Below is the code for a Bubble sort routine.
StrTemp
Swapping array
elements
Private Sub cmdSort_Click()
Dim intInner As Integer
Dim intOuter As Integer
Dim intIndex As Integer
Dim strTemp As String
For intOuter = 0 To intCounter - 1
For intInner = intOuter + 1 To intCounter
If strNames(intOuter) > strNames(intInner) Then
strTemp = strNames(intInner)
strNames(intInner) = strNames(intOuter)
strNames(intOuter) = strTemp
End If
Next intInner
Next intOuter
End Sub
Before
StrNames(intOuter) StrNames(intInner)
Step 1
B
A
A
B
Step 2
Step 3
A
A
B
B
A
Page 32
A
B