Event Procedure in VB.NET


An event is an action that is performed when user interact with particular control.
The event is recognized by the control but it can not perform any action unless you define some code in that event. The code defined along with the event is known as event procedure.
Every control having their own events. For example a button having click event which occurs when user click on a button.
In order to generate event procedure double click on the control. As you double click on the control it will generates default event associated with it as shown below:

Private Sub cmdAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdAdd.Click

End Sub

The default scope of the procedure is private which means you can not access event procedure outside the form.
A control can have one or more events associated with it.
If you want to define event other then default event you can define it by selecting the name of event from event ComboBox available at the top right side of the code window as shown below:
Event Procedure
Event procedure is directly associated with controls so there is no need to call it. It is invoked automatically when user interact with that control. For Example click event of the button is invoked when user clicks the button.

     

Example of Event Procedure


Design an application using Event Procedure to find maximum from two numbers.
Step 1: Design a form as shown below:
Event Procedure
Step 2: Now set properties of various controls as given below:

Control Name Property Name Value

Form1

Text

Max From Two Numbers

Label1

Text

Number1:

Label2

Text

Number2:

TextBox1

Name

txtNumber1

TextBox2

Name

txtNumber2

Button1

Name

cmdMax

Text

Maximum

Label3

Name

lblMax

Text

Maximum Number Is ___

Step 3: Now Double click on Maximum Button and write following code in the click event of button.

If Val(txtNumber1.Text) > Val(txtNumber2.Text) Then
lblMax.Text = "Maximum Number is " & txtNumber1.Text
Else
lblMax.Text = "Maximum Number is " & txtNumber2.Text
End If

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