Usted buscó: addfromstring (Inglés - Ruso)

$zip->addfromstring('foo','new foo');
$zip->addfromstring('foo','new foo');

$zip -> addfromstring ( 'test.txt' , 'filecontentgoeshere' );
$zip -> addfromstring ( 'test.txt' , 'filecontentgoeshere' );

$zip -> addfromstring ( 'afile.txt' , 'index 0' );
$zip -> addfromstring ( 'afile.txt' , 'index 0' );

$zip -> addfromstring ( 'dir/test.txt' , 'filecontentgoeshere' );
$zip -> addfromstring ( 'dir/test.txt' , 'здесьследуетсодержимоефайла' );

$zip -> addfromstring ( 'double.txt' , 'index 1' );
$zip -> addfromstring ( 'double.txt' , 'index 1' );

ziparchive::addfromstring — add a file to a zip archive using its contents
ziparchive::addfromstring — Добавяет файл в zip-архив, используя его содержимое

$zip -> addfromstring ( 'entry1.txt' , 'entry#1' );
$zip -> addfromstring ( 'entry1.txt' , 'entry#1' );

$zip -> addfromstring ( 'dir/double.txt' , 'index 2' );
$zip -> addfromstring ( 'dir/double.txt' , 'index 2' );

$zip -> addfromstring ( 'dir/entry2d.txt' , 'entry#2' );
$zip -> addfromstring ( 'dir/entry2d.txt' , 'entry#2' );