How to add a file to a zip file that the server already exists with PHP

How to add a file to a zip file that the server already exists with PHP
Note that instead of generating a zip, add a file inside without unlocking the server zip file. May I ask how I should do it.

------Solution--------------------
Add a zip module in.
Use the following methods:

$zip = new Ziparchive ();
$filename = "./test112.zip";

if ($zip->open ($filename, ziparchive::create)!==true) {
Exit ("Cannot open < $filename >\n");
}

$zip->addfromstring ("Testfilephp.txt". Time (), "#1 This is a test string added as testfilephp.txt.\n");
$zip->addfromstring ("Testfilephp2.txt". Time (), "#2 This is a test string added as testfilephp2.txt.\n");
$zip->addfile ($thisdir. "/too.php", "/testfromfile.php");
echo "Numfiles:". $zip->numfiles. "\ n";
echo "Status:". $zip->status. "\ n";
$zip->close ();
?>
------Solution--------------------
Also want to say:
1, never blame others do not understand, can only blame themselves did not speak clearly.
2, do not think that they are always right, and occasionally look at others are not said is also right.

