Random Single Image Onload Using PHP

<?php
$imglist='';
//$img_folder is the variable that holds the path to the banner images.
// see that you dont forget about the "/" at the end
$img_folder = "images/";
mt_srand((double)microtime()*1000);
//use the directory class
$imgs = dir($img_folder);
//read all files from the directory, checks if are images and ads them to a list (see below how to display flash banners)
while ($file = $imgs->read()) {
if (eregi("gif", $file) || eregi("jpg", $file) || eregi("png", $file))
$imglist .= "$file ";
} closedir($imgs->handle);
//put all images into an array
$imglist = explode(" ", $imglist);
$no = sizeof($imglist)-2;
//generate a random number between 0 and the number of images
$random = mt_rand(0, $no);
$image = $imglist[$random];
//display image
echo '<img src="'.$img_folder.$image.'" border=0>';
?>