How to compress files from some folder into one ZIP file in PHP?

For a future project I needed these days some easy to use zip or gzip class to create a zip file from files / folders inside a specified directory. A short search on Google has lead me to the Create ZIP File PHP class from Rochak Chauhan. I tested two other scripts before and must say that this script works great for single files if you add them manually. To compress a whole directory with an unknown number of files into one zip file I created some class extension to get this job done.

Create a zip file from folders on the fly