Visual Basic

myRTB.AppendText(myTextBox.Text & Environment.NewLine)

Dim srr As TextReader = New StringReader(rtb.Text)
Dim lineIn As String = ""
While Not (srr.Peek = -1)
lineIn = srr.ReadLine
lineIn = Val(lineIn) + Val(textbox.Text)
End while

Dim newText As New StringBuilder()
For x As Integer = 0 To RichTextBox1.Lines.Length - 1
    newText.AppendLine("test " & RichTextBox1.Lines(x))
Next
RichTextBox1.Text = newText.ToString()

[eg:10(rtb line number)+1(textbox number)=11(10 change to 11)]

Dim newText As New System.Text.StringBuilder
For x As Integer = 0 To RichTextBox1.Lines.Length - 1
    Dim val As Integer = Integer.Parse(RichTextBox1.Lines(x)) + Integer.Parse(TextBox1.Text)
    newText.AppendLine(val.ToString)
Next
RichTextBox1.Text = newText.ToString.Trim

MAGICIANMERLIN wrote:

but unfortunately i couldn't check textbox.text is empty or not?

Christian Graus wrote:

It sounds like a pretty easy task, you create a thread which calls Directory.GetFiles

Private Sub Main_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    BackWork.WorkerReportsProgress = True
    BackWork.RunWorkerAsync()
End Sub

Private Sub BackWork_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackWork.DoWork
    For Each file In My.Computer.FileSystem.GetFiles("C:\", FileIO.SearchOption.SearchAllSubDirectories)
       'Status is a Label
       Status.Text = file
    Next
End Sub

Private Sub BackWork_ProgressChanged(ByVal sender As Object, ByVal e As System.ComponentModel.ProgressChangedEventArgs) Handles BackWork.ProgressChanged
    Status.Text = file
End Sub