Mine

<?php
  //if the form has not been submitted or the file upload was empty//not set
  if (!isset($_POST['submit']) || !isset($_FILES['userfile']['name']) || empty($_FILES['userfile']['name']) ) {
?>
<!-- The data encoding type, enctype, MUST be specified as below -->
<form enctype="multipart/form-data" action="index2.php" method="POST">
    <!-- MAX_FILE_SIZE must precede the file input field -->
    <input type="hidden" name="MAX_FILE_SIZE" value="30000" />
    <!-- Name of input element determines name in $_FILES array -->
    Send this file: <input name="userfile" type="file" />
    <input type="submit" name="submit" value="Send File" />
</form>

<?php
}
else {  // Something has been submitted

  $exp = explode('.', $filename);
  array_pop($exp);
  

  $uploaddir = '/home/mark36ph/public_html/filez/';
 //$uploadfile = $uploaddir . basename($_FILES['userfile']['name']);
  $random_digit = time(); //Generates the time/date string
  $saveFilename = $random_digit.exp;
  $uploadfile = $uploaddir.$saveFilename;
  

  //$newfilename = implode($random_digit.$exp);
  
 
  function image_valid($type, $byExtension = false) {
    $file_types  = array(
      'image/pjpeg',
      'image/jpeg',
      'image/jpg',
      'image/gif',
      'image/x-png',
      'image/png'
     );
 
     $file_extensions = array('jpg','jpeg','gif','png');
 
     if ($byExtension) {
       return in_array(strtolower($type),$file_extensions);
     }
     else {
       return in_array(strtolower($type),$file_types);
     }
  }

  echo '<pre>';
  if (!image_valid($_FILES['userfile']['type'])) {
    echo 'Sorry you can&rsquo;t upload that. <a href="javascript:history.go(-1)">Go back</a>';
  }
  else {
    if (move_uploaded_file($_FILES['userfile']['tmp_name'], $uploadfile)) {
      echo "File is valid, and was successfully uploaded.\n";
	  echo 'filename: '.$saveFilename;
	  
    }
  }
  print "</pre>";
} // submit check
?>