Hi Jonathan; Because I'm a wise old critter (or serendipity struck - choice is yours), I think that I found the cause of my difficulties. 1: I constructed my own 'new' and 'delete' operators. 2: I am constructing a list processor with a list header which has a count of references to the itself. 3: When the reference count is zero, I delete the header and the list contents. I had expected that the C++ kernel would not participate in this. However, what appears to be happening is that when the C++ kernel sees a delete, the object 'vptr' is removed. This is not the behavior I want. In particular I would like to: 1: Retain the C++ 'delete' operator. 2: Remove the 'vptr' only when I want. Creating a method for a delete seems unnatural and needlessly tedious for someone using the software. Do I have any control over when the 'vptr' is removed? Alternatively, is there a non-gcc dependent way of reinserting the 'vptr' into a deleted (but not yet deleted) class object? I can't actually verify that my analysis is correct. The IDE does not display the 'vptr' for pointers and only provides the 'vptr' for references when the reference is highlighted, not when the variables in scope are displayed. I don't know if my guess is correct. And of course, thanks. art ----- Original Message ---- From: Jonathan Wakely <jwakely.gcc@xxxxxxxxx> To: Arthur Schwarz <aschwarz1309@xxxxxxx> Cc: gcc-help@xxxxxxxxxxx Sent: Sun, October 14, 2012 4:19:13 PM Subject: Re: C++ SEGMENT fault and vtable issues On 14 October 2012 20:29, Arthur Schwarz wrote: > Product Version = NetBeans IDE 7.2 (Build 201207171143) > Operating System = Windows 7 version 6.1 running on x86 > Java; VM; Vendor = 1.7.0_03 > Runtime = Java HotSpot(TM) Client VM 22.1-b02 I doubt your IDE or JVM is relevant. > Cygwin gcc 4.5.3 > gdb 4.5.3 > > I have a problem with my C++ application. I have tried to find what is wrong in > my code and am unsuccessful, and amm hping that you can identify the issue. > > The code fails (for different reasons) in two locations: > [code] > SlipHeader* oldHeader; > delete oldHeader; // SEGMENT fault; custom defined delete > > SlipHeader* header; > stringstream pretty; > pretty << header->toString(); // call to pure virtual function > [/code] Clearly this isn't the real code, because oldHeader and header are never initialized. If you show the real code, preferably reduced to the minimum necessary to demonstrate the problem, then someone might be able to suggest where to look for the bug. It sounds like using an object after it's been deleted or some other memory/lifetime issue. On GNU/Linux I'd use valgrind to check for that sort of problem. There are tools to do a similar job on Windows, but the only one I've tried is far inferior to valgrind and isn't free (as in beer or freedom) so I won't recommend it.
