Compressing an entire directory

Hello

I have currently written a simple program to backup a database for a project we are working on here in school, currently its just using a system command to tar.gz an entire director including subfolders. But I found out that we are not allowed to use system commands in the code anymore. So I have to find another way to deal with this, any suggestions ? Note that I have to be able to compress several directories and files under them into 1 file. I have an idea that will read byte for byte of all the files and stuff, but that seems to be a long and tricky thing to do.

Tnx for any help and/or directons in how to do this.

http://burks.bton.ac.uk/burks/software/sources/

That site has a lot of source code, including a good section on encryption, and I think compression.