Usercontrol action event with TextBox

I am new to asp.net, My problem is I have one TextBox and user control Button in default.aspx ,After clicking the Button I need change the text value of TextBox(some default val开发者_如何学运维ue from user control).

Is that possible?If Yes,where i need to write the code?

Default.aspx

<%@ Register Src="Text.ascx" TagName="Edit" TagPrefix="uc1" %> 
<asp:TextBox ID="TextBox1" runat="server" Width="262px"></asp:TextBox>
<uc1:Edit Id="Edit2" runat="server" /></td>

Usercontrol - button

<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="Text.ascx.cs" Inherits="WebApplication4.WebUserControl1" %>
<asp:Button ID="Button1" runat="server" Text="Edit " OnClientClick="return confirm('Are you certain you want to Navigate?');" Width="341px" onclick="Button1_Click" />

how to group or ,fire that(text box value change) from usercontrol ?

Starting from your user control:

<asp:Button ID="Button1" runat="server" Text="Edit " 
    OnClientClick="return confirm('Are you certain you want to Navigate?');" 
    Width="341px" onclick="Button1_Click"/>

In the code behind use this to create a custom event which fires on the button'c click

using System;
using System.Web.UI;

namespace TestApplication
{
    public partial class Edit : UserControl
    {
        public string DefaultValue { get; set; }
        protected void Page_Load(object sender, EventArgs e)
        {

        }
        private static object EditClickKey = new object();
        public delegate void EditEventHandler(object sender, EditEventArgs e);
        public event EditEventHandler EditClick
        {
            add
            {
                Events.AddHandler(EditClickKey, value);
            }
            remove
            {
                Events.RemoveHandler(EditClickKey, value);
            }
        }
        protected void Button1_Click(object sender, EventArgs e)
        {
            OnEditClick(new EditEventArgs(DefaultValue));
        }
        protected virtual void OnEditClick(EditEventArgs e)
        {
            var handler = (EditEventHandler)Events[EditClickKey];
            if (handler != null)
                handler(this, e);
        }

        public class EditEventArgs : EventArgs
        {
            private string data;
            private EditEventArgs()
            {
            }
            public EditEventArgs(string data)
            {
                this.data = data;
            }
            public string Data
            {
                get 
                {
                    return data;
                }
            }
        }
    }
}

The "Default.aspx" page will contain the Event Handler for your new Custom Event.
markup:

<asp:TextBox ID="TextBox1" runat="server" Width="262px"></asp:TextBox>
    <uc1:Edit ID="Edit1" runat="server" OnEditClick="EditClick_OnEditClick" DefaultValue="default" />

Code Behind:

protected void EditClick_OnEditClick(object sender, TestApplication.Edit.EditEventArgs e)
        {
            TextBox1.Text = e.Data;
        }

In the Button1_Click event of Button1 you can get the reference to TextBox using Page.FindControl() method, like this:

protected void Button1_Click(...)
{
     TextBox txtBox = (TextBox)this.Page.FindControl("TextBox1");
     if(txtBox != null)
        txtBox.Text = "Set some text value";
}