Question

I haven’t done any C++ in a while, but decided to finish a big project I was working on for someone. I am getting the following error message now though…

HEAP CORRUPTION DETECTED: after Normal Block (#1761) at 0x17DEB940.
CRT Detected that the application wrote to memory after end of heap buffer.

I have been stepping through all of the functions I thought might have caused it but I am at a loss. Is there any way using the more advanced debugging features to hunt this down?

Answer 1

It does sound like a classic memory corruption error. The platform would be helpful information. Without seeing your code and it’s complexity there are a couple of possibilities:

1. I’ll make a guess that the runtime
   library would allow you to add calls to the
   heap validation code directly from
   your code. I would suggest placing
   calls to the heap validation code in
   various places in your code so you
   can figure out where things go
   wrong. You’ll find the place where
   the heap goes bad and you’ll know
   that it was ok at the previous call.
   Keep narrowing down that window if
   you need to and then review the code
   where the problem occurs.

2. If the same steps corrupt exactly the same place in memory,
   you should be able to use your
   debugger to set a breakpoint (or watchpoint) on the
   memory getting changed. Some of
   those changes may be intended, but
   you should be able to figure out
   which one is the culprit.

You might use a combination of the two if your code is particularly complex or the steps needed to reproduce this are long – narrow down a section of code that it problematic and then place a breakpoint on the memory location that gets corrupted.

david