初学asp.net，有个有关问题请问下各位_ASP.NET

初学asp.net，有个问题请教下各位
请问用asp.net做一个简单表单，如何用循环遍历所有的控件检查是否为空状态？为空的话就弹出对话框提醒，希望各位教教小弟..

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C# code

         for (int i = 0; i < this.Controls.Count; i++)        {            foreach (Control control in this.Controls[i].Controls)            {                if (control is TextBox)                {                    TextBox txt = (TextBox)control;                    if (txt.Text == "")                    {                        Response.Write("<script>alert('空的');</script>");                    }                }            }        }
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探讨

C# code

        for (int i = 0; i < this.Controls.Count; i++)
       {
           foreach (Control control in this.Controls[i].Controls)
           {
               if (control is TextBox)
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