我試圖從文本框中刪除一行，但不知道確切的行

Question

單擊複選框時，我將一行添加到文本框中。我應該怎麼辦時，該複選框未點擊，要刪除的項目：

Private Sub cbAddress_SelectedValueChanged(sender As Object, e As System.EventArgs) Handles cbAddress.SelectedValueChanged 
if cbAddress.checked = true then 
    dim thetext as string = txtTextbox.text 
    dim theItem as string = "test" 
    txtTextbox.text = thetext & Environment.NewLine & theItem 
else 
    ' i'm try to delete the line. 
    ' I've tried to txtTextbox.text.Remove(blah, blah) 
end if 

，我應該跟蹤哪些行被添加到文本框中選中時將其刪除，或者是有更好的辦法？

Answer 1

你可以只使用String.Replace方法：

Private Sub cbAddress_SelectedValueChanged(sender As Object, e As System.EventArgs) Handles cbAddress.CheckedChanged 
    Dim theItem As String = "test" 
    If cbAddress.Checked = True Then 
     Dim thetext As String = txtTextbox.Text 
     txtTextbox.Text = thetext & Environment.NewLine & theItem 
    Else 
     txtTextbox.Text = txtTextbox.Text.Replace(Environment.NewLine & theItem, "") 
    End If 
End Sub 

Answer 2

更換Environment.NewLine

txtTextbox.Text = txtTextbox.Text.Replace(System.Environment.NewLine, "")