Introduction
This article demonstrates an interesting and very useful concept in ASP.NET.
Question: What is substitution control?
In simple terms "This enables the dynamic update of a portion of a page based on a value received from the method".
Step 1: Create a new web application
![Output1.jpg]()
Step 2: Add a method name for the substitution control
![Output2.png]()
Step 3: The complete code of WebForm1.aspx is as in the following:
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="SubstitutionControlASP.NET.WebForm1" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<center>
<div>
<table>
<tr>
<td colspan="2" align="center">
<asp:Label ID="Label1" runat="server" Text="Substitution Control - ASP.NET" Font-Bold="true"
Font-Size="Large" Font-Names="Verdana" ForeColor="Maroon"></asp:Label>
</td>
</tr>
<tr>
<td>
<asp:Label ID="Label6" runat="server" Text="Please Enter FirstNumber" Font-Size="Large"
Font-Names="Verdana" Font-Italic="true"></asp:Label>
</td>
<td>
<asp:TextBox ID="TextBox4" runat="server"></asp:TextBox>
</td>
</tr>
<tr>
<td>
<asp:Label ID="Label2" runat="server" Text="Please Enter SecondNumber" Font-Size="Large"
Font-Names="Verdana" Font-Italic="true"></asp:Label>
</td>
<td>
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
</td>
</tr>
<tr>
<td colspan="2" align="center">
<asp:Button ID="Button1" runat="server" Text="Addition" Font-Names="Verdana" Width="213px"
BackColor="Orange" Font-Bold="True" OnClick="Button1_Click" />
</td>
</tr>
<tr>
<td colspan="2" align="center">
<asp:Substitution ID="Substitution1" runat="server" MethodName="GetAdd" />
</td>
</tr>
<tr>
<td colspan="2" align="center">
<asp:Label ID="Label5" runat="server" Font-Bold="true" Font-Names="Verdana"></asp:Label>
</td>
</tr>
</table>
</div>
</center>
</form>
</body>
</html>
Step 4: The complete code of WebForm1.aspx.cs is as in the following:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace SubstitutionControlASP.NET
{
public partial class WebForm1 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Button1_Click(object sender, EventArgs e)
{
if (string.IsNullOrEmpty(TextBox4.Text) || string.IsNullOrEmpty(TextBox1.Text))
{
Label5.Text = "Please Enter Some Values";
Label5.ForeColor = System.Drawing.Color.Red;
}
else
{
a = int.Parse(TextBox4.Text);
b = int.Parse(TextBox1.Text);
}
}
static int a, b;
public static String GetAdd(HttpContext context)
{
return (a + b).ToString();
}
}
}
Step 5: The output of the application is as in the following:
![Output3.png]()
Step 6: The updated data output of the application is as in the following:
![Output4.png]()
I hope this article was useful for you.