无效的强制转换异常C#ASP.Net

Question

foreach(Label l in Controls)    // setting all labels' s visbility  on page to true
     l.Visible =true;

但在运行时,我遇到了以下错误

Unable to cast object of type 'ASP.admin_master' to type 'System.Web.UI.WebControls.Label'.

Answer 1

如果其中一个控件不是标签类型,您将收到该错误.

你可以尝试:

foreach(Label l in Controls.OfType<Label>())
{
    l.Visible = true;
}