PHP zipping algorithm

How can we zip two files and save output as output.zip. For example, in gmail you can download all the attachment as a single zip file. How can we write that code using php.

Click more for Source Code:

/**
* Php code for file zip
* Author : Sajith.M.R
* Date: 02-02-2007
*/

/** Include the Pear Library for Zip */
include ('Archive/Zip.php');

/** Create a Zipping Object...
* Name of zip file to be created..
* You can specify the path too */
$obj = new Archive_Zip('test.zip');
/**
* create a file array of Files to be Added in Zip
*/
$files = array('black.gif',
'blue.gif',
);

/**
* creating zip file..if success do something else do something...
* if Error in file creation ..it is either due to permission problem (Solution: give 777 to that folder)
* Or Corruption of File Problem..
*/

if ($obj->create($files)) {
// echo 'Created successfully!';
} else {
//echo 'Error in file creation';
}

?>; // We'll be outputting a ZIP
header('Content-type: application/zip');

// It will be called test.zip
header('Content-Disposition: attachment; filename="test.zip"');

//read a file and send
readfile('test.zip');
?>;

//This will output test.zip to the browser. If you dont want zip file as output (just saving into directory) leave the second part of above code

//This will output test.zip to the browser. If you dont want zip file as output (just saving into directory) leave the second part of above code

Note:

Download the pear library from: http://download.pear.php.net/package/Archive_Zip-0.1.1.tgz

or

install via pear pear install http://download.pear.php.net/package/Archive_Zip-0.1.1.tgz