Intro To VB Net

8/11/2019 Intro To VB Net

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2.1 Introduction

Visual Basic (VB) has become the most popular programming language for

several reasons. VB is easy to learn, which makes it an excellent tool for understanding

elementary programming concepts. In addition, it has evolved into such powerful and

popular product that skilled Visual Basic programmer are demand in the job market.

Visual Basic .NET is the latest version of VB. It is designed to allow the

programmer to develop applications that run under Windows and/or in Web browser

without the complexity generally associated with programming.

2.2 The Windows Graphical User Interface

In this module, you will learn to develop an application that run in the Microsoft

Windows environment. Your application will look like standard windows program.

Microsoft Windows uses a graphical user interface, or GUI (pronounced

gooey). The windows GUI defines how the elements such as labels, textboxes,

buttons, radio buttons checks boxes, list boxes, menus and scroll bars look and function.

As a VB programmer, you have available a toolbox of these elements. Thus, to developthe simple Windows GUI you will:

create new windows, called forms.

use the toolbox to add the various elements, called controls.

By the end of this practical section, the students should be able to:

Describe the process of visual program and development

Identify the element in the Visual Basic project

Write, run, save, print and modify the first Visual Basic Project

Use text boxes, group boxes, check boxes, radio buttons and picture boxes

effectively.


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2.3 Visual Basic Application File

A Visual Basic application, called a solution, can consist of one or more

projects. In this module all of the solutions have only one project, therefore you can

think of one solution is for one project. However for each project can contains one or

more form files. For example, to create the HelloWorld application creates these files :

HelloWorld.sln The solution file. A text file that holds

information about solution and the projects

it contains.

HelloWorld.suo Solution user option file. Store

information about the selected option, so

that all customizations can be restoredeach time you open the solution.

helloForm.vb The .vb file. Holds the definitions of a

form, its controls, and code procedures.

This is a text file that you can open in any

editor.

helloForm.resx A resource file for the form. This text file

defines all resources used by form,

including strings of text, numbers and

graphics.

HelloWorld.vbproj A project file. A text file that describes the

project and lists the files that are included

in the project.

HelloWorld.vbproj.user The project user option file. This text file

holds project option settings, so that the

next time you open the project, all selected

options will be restored.

After you run your project, you will find several more file created by the system.

The only file that you will open directly is the .sln, or solution file.


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2.5 The Visual Studio Environment

Steps by Step: Starting the project

2.5.1 The IDE Start Page

Open the Visual Studio IDE,

In the Start Page (Figure 2.1). Recent projects appear on the list. Here, you enable to

1. open an existing project or

2.

selectNew Projectto begin a new project.

Figure 2.1: Start Page


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2.5.2 The New Project Dialog

In the New Project dialog (Figure 2.2), select Visual Basic Projects in the Project

Type and Windows Application in the Templates box.

Give the project a name and path on this dialog box

Figure 2.2: Begin a new VB. Net project

Click OK


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2.5.3 The IDE Main Windows

Figure 2.3 shows the Visual Studio environments main windows and its various

child windows.

Some windows have tabs that allow you display different contents

The IDE main windows hold the Visual Studio menu bar and the toolbars.

Figure 2.3 : The Visual Studio environment


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2.6 First Visual Basic Project

Steps by Step: Writing your First Visual Basic Project

2.6.1 Start a New Project

Open the Visual Studio IDE as shown in 2.2.

Click on the New Project button. The New Project dialog box opens (Figure 2.4).

Make sure that Visual Basic Projects is selected for project Types and Windows

Application is selected for Templates.

For Location, browse to select the path on your new project.

Enter HelloWorld for the name of the new project.

Click the OK button.

Figure 2.4: Select the path and enter the name for the new project


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2.6.2 Set Up Your Environment

Reset the IDE default layout by choosing

Tools/Options/Environment/General/Reset Window Layout.

Click OK on the both dialog

Figure 2.5:

Point to the icon for the toolbox at the bottom of the windows title bar.

The toolbox window opens. Notice the pushpin icon at the top of the window(Figure

2.6); clicking this icon makes the windows remain on the screen rather than

AutoHide.


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Figure 2.6: The Toolbox window.


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2.6.3 Plan the Project

The first step planning is to design the user interface. Figure 2.7 shows a sketch of

the form that includes a label and two buttons.

Figure 2.7: A sketch of the Hello World form for planning

Push Me

Exit

helloForm

exitButton

MessageLabel

pushButton


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2.6.4 Set Up The Form

Step 1: Point to the label tool in the toolbox and click. Then Move the pointer over the

form.

Step 2: Point to a spot where you want one corner of the label, press the mouse button,

and drag the pointer to the opposite corner. When you release the mouse button,

the label and its default contents (Label 1) will appear as shown on figure 2.8.

Figure 2.8: Draw the label on the form

The label has eight small square handles as shown in figure 2.9, indicating that the

control is currently selected. While a control is selected, you can delete it, resize it or

move it.


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Figure 2.9: The label has eight small handles, indicating that it is selected.

Step 3: Draw a button on the form: Click on the Button toll in the toolbox, position the

crosshair pointer for one corner of the button, and drag to the diagonally

opposite corner. The new button should have selection handles.

Step 4: Create another button using this alternative technique. Point to the Button tool in

the toolbox and double click. A new button will appear on top of the last drawn

control.

Step 5: Keep the new button selected, pointed anywhere inside the button, and drag the

button below your first button.

Step 6: Select each control and move and resize the controls as necessary. Make the two

buttons the same size and line them up.

Step 7: Pont to one of the control and click the right mouse button to display a context

menu. On the context menu, select lock control. This lock control will prevent

you from accidentally moving the controls.


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2.6.5 Set Properties

Set the Name and Text Properties for the Label

Step 1: Click on the label on the form (a shaded outline appears around the control).

Next click on the title bar of the properties windows to make it the active

windows.

Figure 2.10: The selected control is shown in the Properties windows

Notice that the Object box at the top of the properties window is showing

Label1(the name of the object) and System.Windows.Forms.Label as the class of the

object. The actual class is Label: System.Windows.Forms is called the namespace, or

the hierarchy used to locate the class.

Step 2: Find the Name property by using scroll up or down. Click the Alphabetic

button at the top of properties windows to arrange all properties should be in

alphabetic order. Click on Name and notice that the Setting box shows Label1.

The Name property is used to refer to the control in program code.


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Figure 2.11: The properties Window

Step 3: Change Label1 with messageLabel (without the quotation marks) as shown in

figure 2.11. Press Enter or Tab and use can see the new name in the Object boxs

drop-down list.

Figure 2.12: Change Label Name

Step 4: Click on the Text property, the Text property is a control to determine what will

be displayed on the form.


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Step5: Double click on Label1 in the Settings box. Then press the Delete key to delete

the value on the Text property as shown in figure 2.13. Then press Enter and

Notice that the label on the form+ now appears empty.

Figure 2.13: Delete the value in for Text Property

Setting the Name and Text properties for the First button

Step 1: Select the first button and then look at the Properties windows. The Object box

shows the name is Button1 and class is System.windows.forms.Button.

Step 2: Change the Name property of the button to pushbutton (without the quotation

marks)

Step 3: Then find Text property and change to PushMe (without the quotation marks)

in the setting box.


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Setting the Name and text properties for the Second button

Step 1: Select Button2 and change the Name property in the properties windows to

exitButton

Step 2: Then change the Text property to Exit

Setting Properties of Form

Step 1: Click anywhere on the form (except on a control). Then the properties window

object box should show the form as the selected object.

Step 2: Change the Text property to My first Hello world Then your form should

now look like figure 2.14

Step 3: Click on the StartPosition propertyand select CenterScreen in order to make

your form in the center of the screen when the program runs.

The forms Text property appears in the title bar

Figure 2.14 : Change the forms text property


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Set the projects Startup Object.

Each project has a Startup Object which is the object with which the project begins.

Step 1: In the Solution Explorer, click on HelloWorld to select the project. Then select

Project/Proerties. In the projects property Pages dialog box, drop down the list

for startp object and select helloForm. Press Apply button and OK.

Figure 2.16 : The Projects Startup Object

Write Code for Hello World

Code the click Event for the Push Me Button

Step 1: Double click the Push Me Button. The visual Studio opens with the first and last

lines of sub procedure already in place.

Step 2: Type this remark statement

Display the hello Message

Step 3: Then type this assignment statement as shown on figure xxx :

MessageLabel.Text=Hello world

Remark statements, or sometimes called comments is use to make the

project more readable and understandable by the people who read it.

They a re not consider executable and no effect when the project runs.

The Assignment statement assigns a value to a property or variable.


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Figure 2.17 : The pushbutton_Click event procedure

Step 4: Return to the form by clicking on helloForm.vb in the Solution Explorer.

Code the Click Event for the Exit Button

Step 1: Double click the Exit button to open the editor for exitButton_Click event.

Step 2: Type this remark:

Exit the project

Then type this Basic statement

Me.Close()

Run the project

After finished writing the code and you ready to run the project. Use one of these three

techniques:

1. Open the Debug menu and choose Start.

2. Press the start button on the toolbar

3. Press F5, the shortcut key for the Start command.

Now click the Push Me button. Your Hello world message appears in the label. Click

the Exit button when you are ready to terminate the project.


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2.7 User Interface Design

User Interface is one of important factor when you design your project User

interface provides a mechanism for end users to interact with the project. Designing

a good interface makes the project easy and simply for the user to use andunderstand.

2.7.1 Introducing More Control

Figure 2.18 shows several more control types: type boxes, group boxes, check

boxes, radio batons and picture box . Figure 2.19 shows some these controls on a

form. Each class of controls has its own set properties. You can see a complete list

of the properties for any class of control by placing a control on a form and examine

the properties list.

Figure 2.18: The toolbox showing the more controls.

Text box

Check box

Grou box

Radio button

Picture box


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Figure 2.19: This form uses textboxes, a check box, radio buttons, buttons and a

picture.

Text Box

A text box control is used to accept input from user or used to display text. The

form in figure xxx has two text boxes. You can simply cut and paste to make

another text box. In program code you can use Text propertyof each text box.

nameLabel = nameTextbox.Text

In this example whatever the user enters into the text box is assigned to the Text

property of nameLabel. If you want to display some textin a text box during

program execution, assigne a literal to the Text property:

positionTextBox.Text = Ahmand, Manager.

You can set the TextAlign propertyof text boxes to change the alignment of

text within the box. In the Properties window, set the property to Left, Right or

Center. In code, you can set property using these values:


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HorizontalAlignement.Left

HorizontalAlignement.Right

HorizontalAlignement.Center

positionTextBox.TextAlign = HorizontolAlignment.Left

Group box

A group box is used as container for other control. Usually, groups of text boxes,

radio buttons or check boxes are placed in group boxes. Using group boxes can

make your forms easier to understand

Check Box

A check box allows the user to select an option. In any group of check boxes, any

number can be selected. The Checked propertyof a check box is set to False if

unchecked and True if checked.

Radio Button

Use a radio button when only one button of group may be selected. Any radiobuttons that you place directly on the form function as a group. A group of radio

buttons inside a group box function together. The best method is to first create a

group box and then create each button inside the group box. The Checked property

of a radio button is set to true is selected or to False if unselected.

Picture Box

A PictureBox control can hold an image. You can set a picture boxs Image

propertyto a graphic file with extension of .bmp, .gif, .jpg, .jpeng, .png, .ico, .emf,or .wmf. First place the pictureBox control on a form and then select its image

property in Properties windows. Click on the Properties button (figure 2.20) to

display an Open dialog box where you can select a file name.


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Figure 2.20: The Image property

You can also use any graphic file (with the proper format) that you have available.

Figure 2.21: The Open dialog box

Properties

button


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2.8 Exercise

1.

Create a project to display company contact information. Include buttons and

label for the contact person, department and phone. When the user clicks on one

of the buttons, display the contact information in the corresponding label.

Include a button to exit.

Documents

Intro To VB Net