VB Window Form 限制輸入字數 code

VB.net限制只能輸入多少字並大寫，以下是練習。

'TextBox limit character digits user input
    Public Sub limitTextBoxDigits(ByRef obj As System.Windows.Forms.TextBox, ByVal digits As Integer)
        obj.CharacterCasing = Windows.Forms.CharacterCasing.Upper
        If obj.SelectedText <> "" Then 
            Dim selIdx As Integer = obj.SelectionStart
            obj.Text = obj.Text.Remove(obj.SelectionStart, obj.SelectionLength)
            obj.Select(selIdx, 1)
        End If
        If obj.Text.Length >= digits Then obj.Text = obj.Text.Remove(digits - 1, 1) : obj.Select(digits - 1, 1)
    End Sub