Thread: Debugging a rare / unreproducible bug..

For bounds checker, I really recommend using Visual Studio because it provides very nice debugging tools, including check for overruns, both on stack and heap.
Another good idea when something goes wrong is typically using Just-in-time (JIT), which can point you to a line of code that crashed a program. Visual Studio supports this.
Or you can attach a debugger to it and hope it crashes, at which time the debugger can catch the line it occured at.

Anyway, as people have pointed out already, you should fix the debug errors first and they are very likely the problem.
As for debugging "unknown" problems, the first thing you have to do if figure out what type of error you get. Very common errors are double-free, using deleted pointers, buffer overruns and clobbering memory. Good debuggers and tools spot many of these common problems.

Originally Posted by dwks

It's a program that examines your code, without compiling it or running it, and identifies bad practises or possible buffer overruns and that kind of thing. I've used splint before, and it works pretty well.
Wikipedia page: http://en.wikipedia.org/wiki/Splint_...amming_tool%29
Download page: http://www.splint.org/
Windows download page: http://www.splint.org/win32.html


It's a program or a library that examines your program as it is run, detecting any buffer overruns or memory errors. The only one I've really used is Valgrind, which is fantastic, but unfortunately only runs under Linux. I've heard of Purity, Electric Fence, and dmalloc(), but never tried any of them.

AFAIK, valgrind is a profiler, CMIIW. I've used it before to check for a bottleneck when I was developing an application for Linux last year.

I've looked at Purity. It's commercial, right? Dunno if my boss would want to buy it. Is there any open source one?

Originally Posted by twomers

>> Right, maybe I'll have a look at the code. Thanks.
For a program bug? Really? You sure that's the way to do it?

Not really. But it's my only lead so far.

Originally Posted by g4j31a5

AFAIK, valgrind is a profiler, CMIIW. I've used it before to check for a bottleneck when I was developing an application for Linux last year.

Well, Valgrind is really an instruction framework that lets a program be executed in a sort of virtual machine, if you know what I mean. The most common use of this (that I can tell) is for memory error detection -- every malloc()/free() call and every variable access can be trapped and examined -- but I'm sure you can do other things with it as well.

Believe me, Valgrind can detect memory leaks and very strange memory errors. That's all I use it for, and I probably use it several times a week.

I've looked at Purity. It's commercial, right? Dunno if my boss would want to buy it. Is there any open source one?

I believe you can download a trial or something. As Elysia said, though, you can just use Microsoft's built-in functions if you're using one of their compilers. http://www.codeproject.com/KB/applic...kdetector.aspx

Other suggestions: http://www.thefreecountry.com/source...ebugging.shtml