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XHTML 1.1 Escaping (Chapter Excerpt 3)

One thing you will inevitably notice when working with the ultra strict XHTML 1.1 is how the ampersand (&) works. In HTML you never had to worry much about the ampersand, though you could use it to implant an HTML space ( ). Now given that XHTML is XML, you simply can't get by with the rules of HTML. In the XML world, if you want to save an XML document with an ampersand, then you have to escape it. If you are familiar with C-based programming languages, then you know all about special characters like this. In those languages you have to "escape" certain characters such as the backslash (\), with another backslash.

In fact, in Altova's XMLSpy application you will get a stopping warning if you have XML that looks something like <b>&</b>. The appropriate way to have an ampersand in XML is to write it as &amp;. This is very similar to what you could do with the   space in HTML and it's not that far off from what we already do. For instance, if you wanted to write &nbsp;. In fact if you want to write &amp;nbsp; you have to write &amp;amp;nbsp. So, if you know HTML, you already know the fundamentals of this rule. It's just that in the strict world of XHTML 1.1, you can no longer let little mistakes enter your code.

Now this rule about dealing with ampersands doesn't end with standalone ampersands, but also applies to ampersands in links. For instance, you can't just have a link like default.aspx?id=3&category=5. Your link has to transform to default.aspx?id=3&category=5.

Fortunately ASP.NET 2.0 is smart enough to deal with things like this in your databinding. For instance, look at the following code...

ASP.NET 2.0 Code

<asp:GridView ID="gvLinks" runat="server"></asp:GridView>

Code Behind

C#

String[] links = new String[] { "http://jampad.net/default.aspx?id=1&name=2", "http://jampad.net/default.aspx?id=1&name=2&frog=3", "Amburgers & Wootbeer" };
gvLinks.DataSource = links;
gvLinks.DataBind( );

Believe it or not, ASP.NET will output produce the following...

<table cellspacing="0" rules="all" border="1" id="gvLinks" style="border-collapse: collapse;">
    <tr>
        <th scope="col">Item</th>
    </tr>
    <tr>
        <td>http://jampad.net/default.aspx?id=1&amp;name=2</td>
    </tr>
    <tr>
        <td>http://jampad.net/default.aspx?id=1&amp;name=2&amp;frog=3</td>
    </tr>
    <tr>
        <td>A&W</td>
    </tr>
</table>

While I'm not a big fan of looking at table code, I am however a huge fan of automation. As you can see here, you don't have to fight with manually escaping data binding ampersands. Thus, you can give ampersands in XHTML data binding a vote towards deterministic.