Lesson 5: Working with Controls in VB2022

Welcome to Lesson 5 of our Visual Basic 2022 Tutorial! In this lesson, you'll learn how to effectively work with TextBox and Label controls. These essential components allow you to create applications that accept user input, display results, and provide clear user guidance.

5.1 Basic Calculator with TextBox

Let's create a simple addition calculator using TextBox controls. This example demonstrates how to accept user input, convert text to numbers, perform calculations, and display results.

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    ' Convert text to numbers and add them
    Dim sum As Double = Val(TextBox1.Text) + Val(TextBox2.Text)
    
    ' Display the result in a message box
    MsgBox("The sum is " & sum)
End Sub

Behavior: This program adds the values from both text boxes and displays the result in a message box.

5.2 Enhanced Calculator with Labels

Let's improve our calculator by adding Label controls for a better user experience. Labels provide context and display results without interrupting the user with message boxes.

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    ' Convert text to numbers and add them
    Dim result As Double = Val(TextBox1.Text) + Val(TextBox2.Text)
    
    ' Display the result in the label
    LblSum.Text = result.ToString()
End Sub

Behavior: When the button is clicked, the sum is displayed in the label instead of a message box.

5.3 Input Validation with TextBox

Validating user input is crucial for creating robust applications. This example demonstrates how to validate input and provide feedback to users.

Private Sub BtnVerify_Click(sender As Object, e As EventArgs) Handles BtnVerify.Click
    ' Check if input is numeric
    If Not IsNumeric(TxtAge.Text) Then
        LblResult.Text = "Please enter a valid number!"
        LblResult.ForeColor = Color.Red
        Return
    End If
    
    ' Convert to number
    Dim age As Integer = CInt(TxtAge.Text)
    
    ' Validate age range
    If age < 0 Or age > 120 Then
        LblResult.Text = "Please enter a realistic age!"
        LblResult.ForeColor = Color.Red
    ElseIf age >= 18 Then
        LblResult.Text = "Access granted. Welcome!"
        LblResult.ForeColor = Color.Green
    Else
        LblResult.Text = "Access denied. You must be 18 or older."
        LblResult.ForeColor = Color.Red
    End If
End Sub

This example demonstrates:

• Using IsNumeric() to validate input
• Converting text to integer with CInt()
• Implementing range validation
• Dynamically changing Label properties (text and color)

5.4 Dynamic Content with Labels

Labels can display dynamic content based on user input or system information. This example creates a personalized greeting.

Private Sub BtnGreet_Click(sender As Object, e As EventArgs) Handles BtnGreet.Click
    ' Get current time
    Dim currentTime As DateTime = DateTime.Now
    Dim hour As Integer = currentTime.Hour
    
    ' Determine time of day
    Dim timeOfDay As String
    If hour < 12 Then
        timeOfDay = "morning"
    ElseIf hour < 18 Then
        timeOfDay = "afternoon"
    Else
        timeOfDay = "evening"
    End If
    
    ' Create personalized greeting
    Dim greeting As String = $"Good {timeOfDay}, {TxtName.Text}!"
    
    ' Display greeting and current time
    LblGreeting.Text = greeting
    LblTime.Text = $"Current time: {currentTime.ToString("hh:mm tt")}"
End Sub

This example shows:

• Working with DateTime functions
• Using string interpolation for dynamic text
• Displaying multiple pieces of information in labels
• Creating personalized user experiences

Next Lesson

Ready to learn about more advanced controls? Continue to Lesson 6: Working with ListBox and ComboBox.

Visual Basic 2022 Made Easy

by Dr. Liew Voon Kiong

The ultimate beginner-friendly guide for mastering Windows-based application development using Visual Basic in Visual Studio 2022. Whether you're a student, teacher, hobbyist, or self-learner, this book offers a clear, step-by-step approach to help you get started with ease.

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• Using controls such as buttons, text boxes, and combo boxes
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