The '-l' option to gcc and g++ is sent to the linker and tells the
linker what libraries you want to link against. If your program has
any symbols (references) in it to things like QString (a Qt class) the
linker will complain that it can't resolve the symbol. When you add
the proper -l options the linker will find it in the appropriate
library.
-lqt tells the linker you want to link against the library found in
the file libqt.so (might have some numbers for versioning after the
.so). If you don't have a that file the linker will tell you it can't
find it. This should be provided by the "libqt" package (or something
similar, I don't use Qt myself).
The *-dev packages have the header files in them (the things used by
the #include parts of a program). If those are missing you get a
different error much earlier. You don't need the -dev package to
_link_ the program if you already have object files (*.o). (You do
need them for a comlete compile from source)
To solve your problem I would suggest trying to find libqt.so and make
sure you have the Qt package(s) installed.
HTH,
-D
PS. I know the above was probably a bit confusing. C/C++ compilation
has several stages, and there are a lot of details related to each
one. There are a lot of details I don't know.
