Visual Basic 2008 Tutorial

 Lesson 2: Working With Controls

Controls  in VB2008 are useful tools that can be placed in the form to perform various tasks. They are used to create many kinds of Windows applications. The diagram on the right is the Toolbox that contains the  controls of VB2008. They are categorized into Common Controls, Containers, Menus, Toolbars, Data, Components, Printings and Dialogs. At the moment, we will focus on the common controls. Some of the most used common controls are Button, Label, ComboBox, ListBox, PictureBox, TextBox etc. To insert a control into your form, you just need to drag the control and drop it into the form. You can reposition and resize it  as you like. Lets examine a few programs that made use of  Button, Label, TextBox , ListBox and PictureBox . You don't have to worry so much about the code because I will explain the program syntax as you progress to later lessons.

 

2.1 Using Text Box-A multiplication program

In this program, you insert two textboxes , three labels and one button. The two textboxes are for the users to enter two numbers, one label is to display the multiplication operator and the other label is to display the equal sign. The last label is to display the answer.

The Code
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

Dim num1, num2, product As Single
num1 = TextBox1.Text
num2 = TextBox2.Text
product = num1 * num2
Label3.Text = product

End Sub

2.2 Using the ListBox-A program to add items to a list box

This program will add one item at a time as the user enter an item into the TextBox and click the Add button.

2.3 Using the PictureBox In this program, we insert a PictureBox and a Button into the form. Make sure to set the SizeMode property of the PictureBox to StretchImage so that the whole picture can be viewed in the picture box. Key in the code as shown below and you can load an image from a certain image file into the PictureBox. Public Class Form1 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click 'To load an image into the PictureBox from an image file PictureBox1.Image = Image.FromFile("c:\Users\Public\Pictures\Sample Pictures\Frangipani Flowers.jpg") End Sub

Class Frm1 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim item As String item = TextBox1.Text 'To add items to a listbox ListBox1.Items.Add(item) End Sub End Class

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