<?php
// Configuration - Your Options
$allowed_filetypes = array('.rar','.png','.zip','.jpg'); // These will be the types of file that will pass the validation.
$max_filesize = 5242880; // Maximum filesize in BYTES (currently 0.5MB).
$upload_path = './files/'; // The place the files will be uploaded to (currently a 'files' directory).

$filename = $_FILES['userfile']['name']; // Get the name of the file (including file extension).
$ext = substr($filename, strpos($filename,'.'), strlen($filename)-1); // Get the extension from the filename.

// Check if the filetype is allowed, if not DIE and inform the user.
if(!in_array($ext,$allowed_filetypes))
die('The file you attempted to upload is not allowed.');

// Now check the filesize, if it is too large then DIE and inform the user.
if(filesize($_FILES['userfile']['tmp_name']) > $max_filesize)
die('The file you attempted to upload is too large.');

// Check if we can upload to the specified path, if not DIE and inform the user.
if(!is_writable($upload_path))
die('You cannot upload to the specified directory, please CHMOD it to 777.');

// Upload the file to your specified path.
if(move_uploaded_file($_FILES['userfile']['tmp_name'],$upload_path . $filename))
echo 'Your file upload was successful, view the file <a href="' . $upload_path . $filename . '" title="Your File">here</a>'; // It worked.
else
echo 'There was an error during the file upload. Please try again.'; // It failed .

?>