How To Force File Download Of A .php File?

Header( "Content-Type: application/octet-stream" );
Header( "Content-Length:" . filesize( $pathToFile) );
Header( "Content-Disposition: attatchment; filename=$pathToFile" );
readfile( $pathToFile);

$pathToFile = 'fileToDownload.php';
Header( "Content-Type: application/octet-stream" );
Header( "Content-Length:" . filesize( $pathToFile) );
Header( "Content-Disposition: attatchment; filename=$pathToFile" );
readfile( $pathToFile);

//This is the php file you want to force the download of...
//This is the php file you want to force the download of...
//This is the php file you want to force the download of...
//This is the php file you want to force the download of...
//This is the php file you want to force the download of...
//This is the php file you want to force the download of...
//This is the php file you want to force the download of...
//This is the php file you want to force the download of...

function output_file($file, $name, $mime_type='')
{
 /*
 This function takes a path to a file to output ($file), 
 the filename that the browser will see ($name) and 
 the MIME type of the file ($mime_type, optional).
 
 If you want to do something on download abort/finish,
 register_shutdown_function('function_name');
 */
 if(!is_readable($file)) die('File not found or inaccessible!');
 
 $size = filesize($file);
 $name = rawurldecode($name);
 
 /* Figure out the MIME type (if not specified) */
 $known_mime_types=array(
  "pdf" => "application/pdf",
  "txt" => "text/plain",
  "html" => "text/html",
  "htm" => "text/html",
 "exe" => "application/octet-stream",
 "zip" => "application/zip",
 "doc" => "application/msword",
 "xls" => "application/vnd.ms-excel",
 "ppt" => "application/vnd.ms-powerpoint",
 "gif" => "image/gif",
 "png" => "image/png",
 "jpeg"=> "image/jpg",
 "jpg" =>  "image/jpg",
 "php" => "text/plain"
 );
 
 if($mime_type==''){
  $file_extension = strtolower(substr(strrchr($file,"."),1));
  if(array_key_exists($file_extension, $known_mime_types)){
  $mime_type=$known_mime_types[$file_extension];
  } else {
  $mime_type="application/force-download";
  };
 };
 
 @ob_end_clean(); //turn off output buffering to decrease cpu usage
 
 // required for IE, otherwise Content-Disposition may be ignored
 if(ini_get('zlib.output_compression'))
  ini_set('zlib.output_compression', 'Off');
 
 header('Content-Type: ' . $mime_type);
 header('Content-Disposition: attachment; filename="'.$name.'"');
 header("Content-Transfer-Encoding: binary");
 header('Accept-Ranges: bytes');
 
 /* The three lines below basically make the 
    download non-cacheable */
 header("Cache-control: private");
 header('Pragma: private');
 header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");

// multipart-download and download resuming support
 if(isset($_SERVER['HTTP_RANGE']))
 {
 list($a, $range) = explode("=",$_SERVER['HTTP_RANGE'],2);
 list($range) = explode(",",$range,2);
 list($range, $range_end) = explode("-", $range);
 $range=intval($range);
 if(!$range_end) {
  $range_end=$size-1;
 } else {
  $range_end=intval($range_end);
 }
 
 $new_length = $range_end-$range+1;
 header("HTTP/1.1 206 Partial Content");
 header("Content-Length: $new_length");
 header("Content-Range: bytes $range-$range_end/$size");
 } else {
 $new_length=$size;
 header("Content-Length: ".$size);
 }
 
 /* output the file itself */
 $chunksize = 1*(1024*1024); //you may want to change this
 $bytes_send = 0;
 if ($file = fopen($file, 'r'))
 {
 if(isset($_SERVER['HTTP_RANGE']))
 fseek($file, $range);
 
 while(!feof($file) && 
  (!connection_aborted()) && 
  ($bytes_send<$new_length)
       )
 {
  $buffer = fread($file, $chunksize);
  print($buffer); //echo($buffer); // is also possible
  flush();
  $bytes_send += strlen($buffer);
 }
 fclose($file);
 } else die('Error - can not open file.');
 
die();
} 
 
/*********************************************
   Example of use
**********************************************/ 
 
/* 
Make sure script execution doesn't time out.
Set maximum execution time in seconds (0 means no limit).
*/
set_time_limit(0); 
$file_path='that_one_file.txt';
output_file($file_path, 'some file.txt', 'text/plain');