point me to functions to parse the URL? (best one for *this* job?)

Hi all, (PHP newbie here. Newbie-level task to match.) I am RTFM and working on this.. but I am also under deadline, so, I ask you in case you can point me quick where to read... what functions I need to use for this. Incoming URL will look like these, for example: domain.com/unix/asdfsdf.html domain.com/macos/khsdfg.html I need to parse those URLs and set the value of $myfolder to as follows: domain.com/unix/asdfsdf.html $myfolder=unix domain.com/macos/khsdfg.html $myfolder=macos BUT if there is no dir/ in between the domain and file, like so: domain.com/khsdfg.html then I want: $myfolder=default I am playing with $_SERVER['PATH_TRANSLATED'], .. what function will parse that best? I need to also account for when the URL does not have an in-between dir/, nor a filename in it, e.g.: domain.com/ (then again $myfolder=default) TIA! -Govinda