php chmod() bug bigger than mount everest?

I'm writing a filemanager in php3.
everything is quite done except
the chmod-funktion .. I get all kind
of crazy crap.
its a textbox where I can write chmod #
but when i do chmod($file, $chmod);
and $chmod is for ex. set to 0777 or 777
it becomes something completely
useless ..
when i use chmod($file, 0777) the file
gets 777 =)
that sucks..big
I have tried both intval() and settype()
on $chmod ..it does not work