c# - 如何使多个文本框只读

Question

我在通过 stackoverflow 搜索时得到了这个脚本

string commonTextBoxPrefix = "txt";
            foreach (Control c in this.Controls)
            {
                if (c.GetType() == typeof(TextBox) && 
                    c.ID.StartsWith(commonTextBoxPrefix))
                {
                    ((TextBox)c).ReadOnly = true;
                }
            }

但是当我遍历控件时它没有检测到任何其他控件，它只检测到 {System.Web.UI.LiteralControl} 所以循环没有进入

if (c.GetType() == typeof(TextBox)

为什么代码没有检测到文本框和其他控件。 我也尝试了下面的代码

foreach (Control c in parent.Controls)
        {
            if (c.Controls.Count > 0)
            {
                ClearControls(c);
            }
            else
            {
                switch (c.GetType().ToString())
                {
                    case "System.Web.UI.WebControls.TextBox":
                        ((TextBox)c).Text = "";
                        break;
                    case "System.Web.UI.WebControls.CheckBox":
                        ((CheckBox)c).Checked = false;
                        break;
                    case "System.Web.UI.WebControls.RadioButton":
                        ((RadioButton)c).Checked = false;
                        break;
                    case "System.Web.UI.WebControls.DropDownList":
                        ((DropDownList)c).SelectedIndex = -1;
                        break;
                }
            }
        }

但是循环不允许进入条件。为什么循环不检测文本框？如何将多个文本框设置为只读？

Answer 1

对我有用

<asp:Panel ID="Panel1" runat="server">
            <asp:TextBox ID="txt1" runat="server"></asp:TextBox>
            <asp:TextBox ID="txt2" runat="server"></asp:TextBox>
            <asp:TextBox ID="txt3" runat="server"></asp:TextBox>
</asp:Panel>

 protected void Page_Load(object sender, EventArgs e)
{
    ClearTextBoxes(Panel1);
}
protected void ClearTextBoxes(Control control)
{
    foreach (Control c in control.Controls)
    {
        if (c is TextBox && c.ID.StartsWith("txt"))
            ((TextBox)c).ReadOnly = true;
    }
}