Clear All Text Box Using Loop without Using TextBox Name in c#.net

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

namespace adi.Web

{

    public partial class WebForm4 : System.Web.UI.Page

    {

        protected void Page_Load(object sender, EventArgs e)

        {

          

        }

        protected void btn1_Click(object sender, EventArgs e)

        {

            ClearAllTextBox(Page.Controls);

        }

        public void ClearAllTextBox(ControlCollection ctrls)

        {

            foreach (Control ctrl in ctrls)

            {

                if (ctrl is TextBox)

                    ((TextBox)ctrl).Text = string.Empty;

                ClearAllTextBox(ctrl.Controls);

            }

        }

    }

}