using System;using System.Web.UI;using System.Web.UI.WebControls;using System.ComponentModel; using System.Text; namespace Controls{    /// 
    /// MyTextBox2 的摘要说明。    /// 
    [ToolboxData("<{0}:MyTextBox2 runat=server>
     ")]    public class MyTextBox2 : System.Web.UI.WebControls.WebControl,INamingContainer    {        private Label lbl;        private TextBox txt;         protected override void CreateChildControls()        {            base.CreateChildControls ();             lbl = new Label();            lbl.ID = "lbl";            lbl.Style.Add("display", "none");            Controls.Add(lbl);             txt = new TextBox();            txt.ID = "txt";            txt.AutoPostBack = true;            txt.TextChanged += new EventHandler(txt_TextChanged);            Controls.Add(txt);             lbl.Attributes.Add("onclick", "showbox(this,'" + txt.ClientID + "');");             ChildControlsCreated = true;        }         protected override void OnPreRender(EventArgs e)        {            base.OnPreRender (e);            if(txt.Text.Trim().Length == 0)                return;            double t = 0;            try            {                t = double.Parse(txt.Text.Trim());            }            catch(Exception ex)            {                ex.ToString();            }            lbl.Text = t.ToString("c");        }          protected override void RenderChildren(HtmlTextWriter writer)        {            StringBuilder sb = new StringBuilder();             sb.Append("");             this.Page.RegisterStartupScript("MyTextBox2JS", sb.ToString());             lbl.RenderControl(writer);            txt.RenderControl(writer);        }         protected override HtmlTextWriterTag TagKey        {            get            {                return HtmlTextWriterTag.Div;            }        }         private void txt_TextChanged(object sender, EventArgs e)        {            if(txt.Text.Trim().Length == 0)                return;            double t = 0;            try            {                t = double.Parse(txt.Text.Trim());            }            catch(Exception ex)            {                ex.ToString();            }            lbl.Style.Add("display", "block");            lbl.Text = t.ToString("c");            txt.Style.Add("display", "none");        }    }}