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Carl Sagan

HTML Encoder

Have you ever tried to embed some scripting examples into a web page? It doesn't come out looking pretty. This example will show you how to create your own HTML Encoder.

Step 1. ASP.NET TextBox

Using Visual Studio create a new webform page called html-encoder.aspx.

Create an ASP.NET TexBox control called HTMLToEncode.
Create a 2nd ASP.NET TextBox control called EncodedHTML.
Create an ASP.NET Button with a OnClick subroutine called EncodeHTML.

Be sure to include validateRequest=false in your @Page directive or else you'll get warning about dangerous content when you submit the form. After you are finished your form should look like this:

<form  runat=server>
<h3>HTML Encode Input Text</h3>

<p>Type or paste in the text you want to HTML encode, then press the <b>Encode</b> button<br />

<asp:TextBox textmode=multiline rows=15 columns=40 ID=HTMLToEncode runat=server />

<p>&nbsp;</p>

<h3>HTML Encoded Output</h3><br />

<asp:TextBox textmode=multiline rows=15 columns=40 ID=EncodedHTML runat=server />

<p>&nbsp;</p>

<asp:Button id=btnEncode OnClick=EncodeHTML runat=server Text="Encode HTML" />
</form>

Step 2. Code-behind

Edit the code-behind file html-coder.aspx.cs. Using Server.HTMLEncode() you only need one line to assign ecoded value the 2nd ASP.NET TextBox.

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;

public partial class html_encoder : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }

    protected void EncodeHTML(object sender, EventArgs e)
    {
    
        EncodedHTML.Text=Server.HtmlEncode(HTMLToEncode.Text);

    }
}

Test Drive

You can try out the HTML Encoder now.