vb.net - 对于每个文本框循环

Question

我正在尝试创建一个 foreach 循环来检查面板中的每个 TextBox，如果它的 Text 什么都没有，则更改 BackColor。我尝试了以下方法:

Dim c As TextBox
For Each c In Panel1.Controls
  if c.Text = "" Then
    c.BackColor = Color.LightYellow
  End If
Next

但我收到错误:

Unable to cast object of type System.Windows.Forms.Label to type System.windows.forms.textbox

Answer 1

你可以试试这样的:

  Dim ctrl As Control
  For Each ctrl In Panel1.Controls
  If (ctrl.GetType() Is GetType(TextBox)) Then
      Dim txt As TextBox = CType(ctrl, TextBox)
      txt.BackColor = Color.LightYellow
  End If