I'm using OS X Snow Leopard. I have a web application hosted locally in the web server folder with
_www user and
I'm unable to edit those files with my local user, who is part of the group
The best option is to add your local user to the _www group ; that's what groups are there for. Being administrator doesn't mean you own other user's files. You could of course override this using sudo, but this is bad.
Bottom line: add your local user to the _www group and make the files in the web server folder group-writeable (
See this answer on how to add your local user to the _www group.