VB Objects & Events (Exercises)

School of BusinessEastern Illinois University

© Abdou Illia, Spring 2003

(Week 3, Friday 1/31/2003)

2Objects (Controls)

Pointer

Label

Frame

Check Box

Combo Box

Horizontal Scroll Bar

Timer

Directory List Box

Shapes

Image Box

Object Linking Embedding

Picture Box

Text Box

Command Button

Option Button

List Box

Vertical Scroll Bar

Drive List Box

File List Box

Lines

Data Tool

The Toolbox

Command buttons

Text box Picture box

Label

3Objects and Event [Sub]procedures

Name: cmdExitCaption: &Exit

Name: cmdFontSizeCaption: Change Font &Size

Private Sub cmdFontSize_Click() txtName.Font.Size = 18End Sub

Event procedure

Private Sub cmdBold_Click() txtName.Font.Bold = TrueEnd Sub

Event procedure

Private Sub cmdExit_Click() EndEnd Sub

Event procedure

4Event [Sub]procedures’ syntax

[Private | Public] Sub ProcedureName_Event ( ) StatementsEnd Sub

Where:Public means that the Subprocedure is accessible to all otherprocedures in the application

Private means that the Subprocedure is only accessible to allother procedures related to the form

ProcedureName is usually the name of the object associatedto an event

Event is the name of the event that might happen

Statements are the instructions to be executed at run time

5Statements

All statements on slide # 3 are Assignment statements

Assignment statements assign values to Objects’ properties

Example

txtName.Font.Size = 18 Object Property Assigned value

6Assignment Statements syntax

ObjectName.Property[.SubProperty] = Value

Where:ObjectName is the name of the object which property will be assigned a value.

Property is the object’s property which value will be assigned

SubProperty: In some case, properties may have subproperties. Subproperty refer to a particular subproperty.

Value. Also refered to as Setting, Value is the value to be assigned to the property.

7Object, Properties, Events

Each object has its related:– Properties (characteristics like name, color, size, etc.)– Events (actions it respond to)

Different Properties and Events for objects– But all objects have the Name property

Should know common properties and common events for usual objects

8Common properties & eventsObject: Command buttonCommon Properties

- Caption (Text that appear on the button)- BackColor (Color of the background)- Default (True or False)- Enabled (Can respond to User events: True or False)- Font (Font.Name, Font.Size, Font.Bold, Font.Italic..)- Visible (Make object appear or disappear: True or False)

Common Events- Click- GotFocus- LostFocus

9Common properties & eventsObject: Text boxCommon Properties

- Alignment (0-Left, 1-Right, 2-Center)- BackColor (Color of the background)- BorderStyle (Style of the border: 0 or 1)- Enabled (Can respond to User events: True or False)- Font (Font.Name, Font.Size, Font.Bold, Font.Italic..)- ForeColor (Color of the foreground)- Text (Text to be displayed)- Visible (Make object appear or disappear: True or False)

Common Events- GotFocus - Change - KeyPress- LostFocus - Click - KeyUp

10Common properties & eventsObject: Picture box

Common Properties- BackColor (Color of the background)- BorderStyle (Style of the border: 0 or 1)- Enabled (Can respond to User events: True or False)- ForeColor (Color of the foreground)- Picture (specification of a file)- Visible (Make object appear or disappear: True or False)

Common Events- GotFocus, LostFocus, Change, Click, DblClick

Common Methods: - Print - Cls

11Common properties & events

Object: Label

Common Properties- Alignment (0-Left, 1-Right, 2-Center)- Caption (Text that appear on the button)- BackColor (Color of the background)- BorderStyle (Style of the border: 0 or 1)- Font (Font.Name, Font.Size, Font.Bold, Font.Italic..)

Common EventsNote: We usually don’t associate events procedures to Labels even if it is possible to do so.

12Setting colors

At design time– Colors are selected from the palette (in Properties Win.)

When writing code– 8 most common colors can be assigned with the following

color constants:

vbBlack vbRed vbGreen vbYellow

vbBlue vbMagneta vbCyan vbWhite

Examples: txtName.ForeColor = vbGreen

picOutput.BackColor = vbWhite

13Assigning Font settings

At design time– Font settings are assigned from the Properties window

When writing code– Font settings can be assigned using statements like:

txtBox.Font.Size = 18

lblOne.Font.Italic = True

txtBox.Font.Name = “Courier”

txtBox.Font.Underline = True

14Exercises 19-32, page 68

Write a line (or lines) of code to carry out the following:

Display "The stuff that dreams are made of." in red letters in txtBoxAnswer:

Display "Life is like a box of chocolates." in Courier font in txtBoxAnswer:

15Exercises

Delete the content of txtBoxAnswer:

Delete the content of lblTwoAnswer:

16Exercises

Make lblTwo disappearAnswer:

Remove the border from lblTwoAnswer:

Give picBox a blue background

Answer:

17Exercises

Place a bold red "Hello" in lblTwo

Answer:

18Exercises

Place a bold italic "Hello" in txtBoxAnswer:

Make picBox disappearAnswer:

19Exercises

Give the focus to cmdButtomAnswer:

Remove the border from picBoxAnswer:

20Exercises

Place a border around lblTwo and center its contentAnswer:

Give the focus to txtBoxTwoAnswer:

21Problem 1

Consider the following interface and property settings

Object Property Setting

frmEx1 Caption Colorful Text

lblBack Caption Background

cmdRed Caption &Red

cmdBlue Caption &Blue

txtShow Text Beautiful Day

Multiline True

Alignment 2 –Center

lblFore Caption Foreground

cmdWhite Caption &White

cmdYellow Caption &Yellow

Write the code to carry out the following task: Pressing the command buttons alter the background and foreground colors in the textbox.

22Problem 2

Consider the following interface and property settings

Object Property Setting

frmEx2 Caption Sayings

txtQuote Text [Blank]

txtLife Text Life

txtFuture Text Future

txtTruth Text Truth

Write the code to carry out the following task: When you click on one of the three small text boxes at the bottom of the form, an appropriate saying is displayed in the large text box. Use the sayings “I like life, it’s something to do.”; “The future isn’t what it used to be”; and “Tell the truth and run”.

23Problem 3

Consider the following interface and property settings

Object Property Setting

frmEx3 Caption Fonts

txtShow Text [Blank]

cmdCour Caption Courier

cmdSerif Caption MS Serif

cmdWing Caption Wingdings

Write the code to carry out the following task: After the user type something into the text box, the user can change the font by clicking on one of the command buttons.

Other Exercise

(To do later)

25Problem 4: Payroll problem 2

Based on the Program Flowchart and the Pseudocode that follow (see next two slides), create the Visual Basic application for the following payroll problem:

Compute the pay for an employee, assuming that name, Social Security Number, hours worked, and hourly rate are input. The output will be the name, Social Security Number, and pay of the employee. Regular pay will be computed as hours (up through 40) times rates, and overtime pay will be computed at time and half (1.5 times hours times rate) for all the hours worked over 40.

26Problem 4 (Program Flowchart)

READ

NAME, SSN, HOURS, RATE

WRITE

NAME, SSN, PAY

HOURS > 40

?

PAY = REGPAY + OTPAY

PAY =

HOURS * RATE

START

STOP

YESNO

OTPAY = (HOUR – 40) * (1.5 * RATE)

REGPAY = 40 * RATE

27Problem 4 (Pseudocode)

Start

Read NAME, SSN, HOURS, RATE

IF HOURS > 40 THEN

REGPAY = 40 * RATE

OTPAY = (HOURS – 40) * (1.5 * RATE)

PAY = REGPAY + OTPAY

ELSE

PAY = HOURS * RATE

ENDIF

Write NAME, SSN, PAY

Stop

28Problem 4 (VB solution)