PHP: Give An ID to File in XML - php

Question

Im using this code for create a xml file which is listing files' url and descriptions in directory. but i need to add in this xml also number of file. so i want to give to files a number (or ID), like 1 for file 2....n , like counter for every row how i can do this ?
thank you
<?php
$myfeed = new RSSFeed();
// Open the current directory (or specify it)
$dir = opendir ("./");
while (false !== ($file = readdir($dir))) {
if (strpos($file, '.jpg',1)||strpos($file, '.gif',1) ) {
$myfeed->SetItem("http://host.com/images/$file", "$file", "");
}
}
// Output the XML File
$fp = fopen('rss.xml', 'w');
fwrite($fp, $myfeed->output());
fclose($fp);
echo $myfeed->output(); //lets see that
class RSSFeed {
// VARIABLES
// channel vars
var $channel_url;
var $channel_title;
// items
var $items = array();
var $nritems;
// FUNCTIONS
// constructor
function RSSFeed() {
$this->nritems=0;
$this->channel_url='';
$this->channel_title='';
}
// set channel vars
function SetChannel($url, $title, $description, $lang, $copyright, $creator, $subject) {
$this->channel_url=$url;
$this->channel_title=$title;
}
// set item
function SetItem($url, $title, $description) {
$this->items[$this->nritems]['url']=$url;
$this->items[$this->nritems]['title']=$title;
$this->nritems++;
}
// output feed
function Output() {
$output = '<?xml version="1.0" encoding="UTF-8"?>'."\n";
$output .= '<playlist version="0" xmlns = "http://xspf.org/ns/0/">'."\n";
$output .= '<trackList>'."\n";
for($k=0; $k<$this->nritems; $k++) {
$output .= '<track>'."\n";
$output .= '<location>'.$this->items[$k]['url'].'</location>'."\n";
$output .= '<image></image>'."\n";
$output .= '<annotation>'.$this->items[$k]['title'].'</annotation>'."\n";
$output .= '</track>'."\n";
};
$output .= '</trackList>'."\n";
$output .= '</playlist>'."\n";
return $output;
}
};
?>

Answer 1

First up, I don't think creating XML with string-functions is a good idea, rather use a parser like simplexmlor DOM.
Assigning an id to each entry, you could take your $k in function Output():
for($k=0; $k<$this->nritems; $k++) {
$output .= '<track>'."\n";
$output .= "<id>$k</id>\n";
// (...)
$output .= "</track>\n";
}
or add id as attribute to the <track>-node:
$output .= "<track id=\"$k\">\n";