Passing value from User Control to the Page in ASP.NET

Introduction

Here we will discuss that how to pass a value of user control to the page. Now I am going to tell you how to pass the entered value from a user control and pass to it's calling page. Firstly I am going to create a user control(.ascx) and page(.aspx) which is shown in the figure given below.

Step 1: Take a Web Application and add a folder name as User Control.

Step 2: Right click on User Control folder and add a new item name as web user control.

Step 3: Open the .ascx file and take a panel. Inside the panel we have to take a Label, Textbox and a Button.

Step 4: Now open .ascx.cs file and write the code below.

Firstly we have to make a delegate, so create a delegate named SMTPH (string msg) just above the class because delegate always have to be declared above of the class. Create a variable name as msg for the  delegate. Pass the TextBox value to the delegate. Write the code given below.

Code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
 
namespace WebApplication1.NewFolder1
{
    public delegate void SMTPH(string msg);
    public partial class WebUserControl1 : System.Web.UI.UserControl
    {
      
        public event SMTPH sendMsg;
        protected void Page_Load(object sender, EventArgs e)
        {
 
        }
 
        protected void Button1_Click(object sender, EventArgs e)
        {
            if (sendMsg != null)
            {
                sendMsg(TextBox1.Text);
            }
        }
    }
}

Step 5: Open the default.aspx file and drag and drop the WebUserControl.ascx file.

Step 6: In this step you have to open the default.aspx.cs file and write the code given below.

Code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using WebApplication1.NewFolder1;
 
namespace WebApplication1
{
    public partial class _Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            WebUserControl13.sendMsg += delegate(string message)
            {
 
                lblUserControlTextBoxValue.Text = message;
 
            };
        }
    }
}

Step 7: Now press F5 to run the application and enter any value to the TextBox.

Output