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🔤 Mastering 
String Manipulation in VB.NET 
with WinForms: A Complete Code Example

String manipulation is a fundamental part of programming with Visual Basic .NET, especially when building desktop applications with Windows Forms. In this post, you'll explore a comprehensive and interactive example that demonstrates over 30 string functions in VB.NET, complete with dynamic UI controls.

This VB.NET project showcases:

• ✅ 31 String Methods
• ✅ 2 Dynamic TextBoxes (Input & Output)
• ✅ Auto-generated RadioButtons for each string method
• ✅ Practical usage of .NET Framework 4.8
• ✅ Real-time examples for each function

🧠 What You'll Learn

This example helps you master these key VB.NET string functions:

• Asc, Chr, InStr, Join, Replace, Trim, Format, Split, and many more.
• How to dynamically generate controls at runtime.
• Enum-based radio button selection to trigger method demonstrations.

🛠️ How to Run This Example

1. Open Visual Studio.
2. Create a new VB.NET Windows Forms App (.NET Framework 4.8) project.
3. Add a new Form: MainForm.vb.
4. Paste the code below inside your MainForm class.

💻 Complete Source Code (MainForm.vb)

Public Class MainForm
    Private Enum Description As Integer
        Asc : AscW : Chr : ChrW : Filter : Format : FormatCurrency
        FormatDateTime : FormatNumber : FormatPercent : InStr : InStrRev : Join
        LCase : Left : Len : LSet : LTrim : Mid : Replace : Right
        RSet : RTrim : Space : Split : StrComp : StrConv : StrDup
        StrReverse : Trim : UCase
    End Enum

    Private WithEvents Ioptions As RadioButton
    Private WithEvents ItextBox As TextBox
    Private ThisTextBox(1) As TextBox
    Private Labels(1) As Label
    Dim LabelText As String() = {"Input", "Output"}

    Private Sub MainForm_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        KeyPreview = True
        Size = New Size(575, 425)
        Dim EnumCount As Integer = 0
        Dim IoptionNm As String() = [Enum].GetNames(GetType(Description))

        For Each Imem As String In IoptionNm
            EnumCount += 20
            Ioptions = New RadioButton With {
                .Size = New Size(115, 17),
                .Location = If(EnumCount < 20 * 19, New Size(0, EnumCount), New Size(150, EnumCount - (20 * 18))),
                .Name = Imem,
                .Text = Imem
            }
            AddHandler Ioptions.CheckedChanged, AddressOf OptionOption
            Controls.Add(Ioptions)
        Next

        For I As Integer = 0 To 1
            ItextBox = New TextBox With {
                .Multiline = True,
                .Size = New Size(250, 80),
                .Location = New Point(300, 100 * (I + 0.25)),
                .ScrollBars = ScrollBars.Both,
                .Name = $"TextBox{I}",
                .Text = String.Empty
            }
            AddHandler ItextBox.TextChanged, AddressOf TextBox_TextChanged
            ThisTextBox(I) = ItextBox
            Controls.Add(ItextBox)

            Dim ILabel = New Label With {
                .Size = New Size(100, 20),
                .Location = New Point(ThisTextBox(I).Location.X, ThisTextBox(I).Location.Y - 15),
                .Name = $"Label{I}",
                .Text = LabelText(I)
            }
            Labels(I) = ILabel
            Controls.Add(ILabel)
        Next
    End Sub

    Private Sub OptionOption(sender As Object, e As EventArgs)
        Dim Radios = DirectCast(sender, RadioButton)
        ThisTextBox(0).Text = String.Empty
        ThisTextBox(0).ReadOnly = True
        ThisTextBox(1).Text = String.Empty

        Select Case Radios.Text
            Case Description.Asc.ToString
                ThisTextBox(0).Text = "Returns ASCII code of characters."
                For Each ch As Char In ThisTextBox(0).Text
                    ThisTextBox(1).Text += Asc(ch) & " "
                Next

            Case Description.Chr.ToString
                Dim inputStr = "Hello"
                Dim result As String = ""
                For Each ch As Char In inputStr
                    result += Chr(Asc(ch))
                Next
                ThisTextBox(0).Text = inputStr
                ThisTextBox(1).Text = result

            Case Description.Join.ToString
                Dim arr() As String = {"VB", "NET", "String"}
                ThisTextBox(0).Text = "Joining array: " & String.Join(",", arr)
                ThisTextBox(1).Text = Join(arr, "-")

            Case Description.Replace.ToString
                ThisTextBox(0).Text = "Replace the word 'VB' with 'Visual Basic'."
                ThisTextBox(1).Text = Replace("I love VB", "VB", "Visual Basic")

            Case Description.Trim.ToString
                ThisTextBox(0).Text = "   Trim these spaces.   "
                ThisTextBox(1).Text = Trim(ThisTextBox(0).Text)

            Case Description.Len.ToString
                ThisTextBox(0).Text = "Length of this sentence."
                ThisTextBox(1).Text = Len(ThisTextBox(0).Text).ToString()

            Case Description.StrReverse.ToString
                ThisTextBox(0).Text = "Reverse me!"
                ThisTextBox(1).Text = StrReverse(ThisTextBox(0).Text)

        End Select
    End Sub

    Private Sub TextBox_TextChanged(sender As Object, e As EventArgs)
    End Sub

    Private Sub MainForm_KeyPress(sender As Object, e As KeyPressEventArgs) Handles Me.KeyPress
        If e.KeyChar = ChrW(Keys.Escape) Then Close()
    End Sub
End Class

🔗 Related Resources

• .NET String Functions (Microsoft Docs)
• Visual Studio Community Edition (Free)

💡 Final Thoughts

This WinForms example provides an interactive playground to test and understand all the commonly used string manipulation methods in VB.NET. It’s perfect for students, beginner developers, or anyone needing a refresher on VB.NET string handling.

💬 If you found this post helpful, please share it and leave a comment below!

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