对于每个文本框循环 [英] For each textbox loop

问题描述

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:

I'm trying to make a foreach loop that checks every TextBox in a panel and changes BackColor if its Text is nothing. I've tried the following:

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:

无法将 System.Windows.Forms.Label 类型的对象转换为类型System.windows.forms.textbox

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

推荐答案

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

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