Thread: for loop bombing - very strange

The problem probably lies elsewhere, likely undefined behaviour somewhere earlier in the code, but was manifested at this point.

The problem is not in the loop.

The probable cause is some other apparently unrelated code, executed before the loop, that molests a pointer. Examples might be dereferencing a NULL pointer, dereferencing an uninitialised pointer, or falling off the end of an array (eg accessing the 10th element of an array with 5 elements).

Having said that, your response will probably be "Huh? How can code unrelated to a loop affect a loop?" The thing is, invalid operations are allowed to do anything, including overwriting random areas of memory, and the effects are not always immediately visible to the program, let alone to a user of the program. If that random area of overwritten memory affects the value of (say, in your code) nodeCount, then the behaviour of the loop is compromised. Or behaviour of your network simulator is compromised.

Note that pointer molestations are not the only way code can exhibit undefined behaviour. For C programmers, however, they are the most common ways.

Or you could just do what 99% of other people do and run the damn thing in a debugger. That will show you not only the exact line it bombs on, but the values of all variables at that point too, and let you poke the code while its still running.

Seriously, don't go stabbing randomly looking for needles in your haystacks, roll back time and watch the needle being inserted. Despite my "printf" comment in my signature, which works for casual debugging of most simple problems, if you're stumped you should always single-step the program and see where it ACTUALLY crashes and why.