Why are the xml tags not visible?

Could some one please tell me why, when I run the following
php code:

<HTML>
<HEAD>
<TITLE></TITLE>
</HEAD>
<BODY>
<?php  
$readfile = file("rss_file.xml");

for ($k=0; $k<=count($readfile)-1; $k++) {
	    echo "$readfile[$k]<br>";
}

</BODY>
</HTML>

the tags do not appear in output to my firefox browser?

The HTML tags do not appear because parsing stops due to the missing closing php tag. You probably do not have errors displayed by default so you do not see the error. Running on my system on the command line gives exactly the error.