Hi,
i've been programming a while in D (http://www.digitalmars.com/d/) now. I prefer it to Java because it is faster. However, i have not found an Editor that supports Code-Completion and Debugging (Step-Over, Step-Into, Breakpoints,...).
Do you have any suggestions?
P.S: gdb did not work.
Descent, the Eclipse plugin, should support both (if you have a D supporting debugger installed). I have to admit I haven't tried it in a long time though, and when I did, debugging did not work, using gdb.
See also this question
Personally I use Vim which currently provides neither completion nor debugging, although I know a completion engine was started once.
I use descent as well. I don't use it's debugger bit but that is because I'm editing on a windows desktop and building/running/debugging on a Linux server.
I suggest you try the excellent Code::Blocks IDE. It has a very good support for D (it even automatically recognizes DMD and/or GDC D compilers).
Another alternative has already been mentioned above - Descent. I haven't used Descent because whenever I tried it I had problems and at some point I gave up (this does not mean it is bad, it means I am just lazy to figure out what problems were).
C::B uses GDB so I guess (not sure, did not try) you can use patched GDB to debug your code.
Under Linux I use Eclipse (+Descent) or gEdit as IDE and use gdb as debugger.