Public Class Form1
    Dim arrpos() As Int32, pos As Int32
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        If TextBox1.Text.Length > 0 Then
            ListBox1.Items.Clear()
            pos = -1
            ReDim arrpos(TextBox1.Text.Length - 1)
            GetPermutation(0, TextBox1.Text)
        End If
    End Sub
    Private Sub GetPermutation(ByVal p As Int32, ByVal str As String)
        Dim permstr As String = String.Empty
        pos += 1
        arrpos(p) = pos
        If pos = str.Length Then
            For i As Int32 = 0 To arrpos.Length - 1
                permstr &= str.Substring(arrpos(i) - 1, 1)
            Next i
            ListBox1.Items.Add(permstr)
        Else
            For i As Int32 = 0 To str.Length - 1
                If arrpos(i) = 0 Then GetPermutation(i, str)
            Next i
        End If
        pos -= 1
        arrpos(p) = 0
    End Sub
End Class