Html Decode method decodes a particular string which is encoded.

Encoding and decoding is needed in somewhere like

•    Pass the values from one page to another.
•    Access the URL or pass the URL.
•    Fetch the data or insert data in Database.
•    Read the xml data or insert data in xml.
•    Change the special character from string
•    And security purpose etc.

In ASP.Net we used the following encode and decode method:

•    Server.HtmlEncode()
•    Server.HtmlDecode()
•    Server.HtmlUrlEncode()
•    Server.HtmlUrlDecode ()
•    HttpUtility.UrlEncode()
•    HttpUtility.UrlDecode () 

How Use these method in ASP.Net

Server.HtmlEncode():
Syntax:

And

Example:

string strData="?data??";       

Response.Write(Server.HtmlEncode(strData)); //Encode the value here

Server.HtmlDecode()

Syntax:

And

Example:

string strData="?data??";       

Response.Write(Server.HtmlDecode(strData)); //Decode the value here

Server.HtmlUrlEncode()

This function is used for encode the URL

Syntax:

We pass the other parameter as:

string  HttpUtility.UrlEncode(byte[] bytes), string  HttpUtility.UrlEncode(byte[] bytes,System.Text.Encoding e)and string  HttpUtility.UrlEncode(byte[] bytes,int offset,int count)

Example:

string strUrl=Request.Url.ToString();//Request.Url get the url 
Response.Write("<font color='green'>URL is:</font> " + strUrl +"<br/>");
Response.Write("<font color='green'>Encoded URL is: </font>" + HttpUtility.UrlEncode(strUrl));//Encoded Url Here

Output:

 Server.HtmlUrlDecode ()

This function is used for decode the encoded URL

Syntax:

We pass the other parameter as:

string  HttpUtility.UrlDecode(byte[] bytes), string  HttpUtility.UrlDecode(byte[] bytes,System.Text.Encoding e)and string  HttpUtility.UrlDecode(byte[] bytes,int offset,int count)

Example:

string strUrl=Request.Url.ToString();//Request.Url get the url 
Response.Write("<font color='green'>URL is:</font> " + strUrl +"<br/>");
Response.Write("<font color='green'>Encoded URL is: </font>" + HttpUtility.UrlEncode(strUrl) + "<br/>");//Encoded Url Here
Response.Write("<font color='green'>Decoded URL is: </font>" + HttpUtility.UrlDecode(HttpUtility.UrlEncode(strUrl)));//Decoded Url Here

 Output:

HttpUtility.UrlEncode() and HttpUtility.UrlDecode ()

Both method work same as to Server.HtmlUrlEncode() and Server.HtmlUrlDecode() respectively.

 Note:

In Latest version ASP.Net 4.0, we write the code more concise way

Example:

<p><%=Server.HtmlEncode(strData); %> or

<%=HttpUtility.UrlEncode(strData); %></p>

But in Asp.net 4.0 we use as  <%: strData %>, it is similar to both

This is the simple concept on encoding and decoding in ASP.Net.