There are several ways to embed PHP code into HTML documents. One way is to put the PHP code within the tags <? ... ?>:
<? echo "hello, world!"; ?>
Most PHP programmers choose this syntax. If PHP is combined with XML, however, there are conflicts with this syntax. In XML the <? ... ?> construct is a special thing called a processing instruction. If PHP and XML are needed in the same file, one can use the alternative PHP tag <?php ... ?>:
<?php echo "hello, world!"; ?>
Some HTML editors (such as FrontPage) don't like processing instructions, so another alternative is to use the <SCRIPT> tag. This is the syntax:
<SCRIPT LANGUAGE="php"> echo "hello, world!"; </SCRIPT>
And last but not least, the final way is to use a style similar to one in Mason: the <% ... %> tag:
<% echo "hello, world!"; %>
We are not using XML in these examples, so we don't need to use the <?php ... ?> syntax. Also, because our favorite HTML editors are vi and emacs, we don't need the <script> syntax (we don't use FrontPage or other HTML editorsif you do, plan accordingly). We use the first style in our examples.