[ns] How to see the output inside #ifndef DEBUG?

[Noor Asraf]

There are a lot of functions in aodv.cc which have code like these:

#ifdef DEBUG
   fprintf(stderr, "%s: sending RERR...\n", __FUNCTION__);
#endif

To understand the rest of the functionality, I feel it would be better to
know this output. This probably involves enabling DEBUG flag in the makefile
(which one?). Enabling DEBUG, would affect the rest of the code besides
providing useful messages? If anyone know about this, please share. And once
editing the Makefile and compiling, what else do I need to do to see the
output?

Thanks,
Asraf