Debugging changes in code

[NoBugs!]

Is there a way to debug a section of code in an Ubuntu program?

I know you can run "sudo apt-get source programname" to get the program source, you can make modifications and ./configure, make, sudo make install to make changes, but is there any way to debug what a section of code is doing? Such as stepping through the code, using breakpoints, watches, etc?

[NoBugs!]

Can it be debugged with gdb? I installed a gui for gdb-debugging but I couldn't figure out how to start the debugging.

[dinxter]

you can certainly do set breakpoints, watches, step over, break at line number and a whole host of things with gdb. Try the tutorial http://www.delorie.com/gnu/docs/gdb/gdb_toc.html
Using one of the many IDE's with these things built tends to be the way i do it these days though