<?php
 
function thumbList($folder, $thumb, $img)
{
	$banned = array(".", "..", "index.php", "error_log");
 
	//leave blank
	$html = '<ul class="thumbNail">';
 
	if ($handle = opendir($folder)) 
	{
		// List all the files		
		while ( false !== ( $file = readdir($handle) ) ) 
		{
			$pos = strrpos($file, ".");
			$ok = false;
 
			if( !in_array($file, $banned) && $pos )
			{				
				//if file contains _thumb, do not link to it
				if(strstr($file, "_thumb"))
				{
					$ok=false;
				} else {
					$ok=true;
				}
 
				$file = substr($file, 0, $pos);
				//if the item is the normal img, display corresponding thumb and link to large img
				if($ok)
					$html .= "<li><a href='$file$img' title='$file'><img src='$file$thumb' /></a></li>";
 
			}
		}
 
		closedir($handle);
		$html .= '</ul>';
		echo $html;
	}
}
 
 
//Set all your variables here and call the function for each folder
$folder = ".";
$thumb = "_thumb.jpg";
$img = ".jpg";
 
thumbList($folder, $thumb, $img);
 
?> 
</ul>