Within QtCreator, in an Ubuntu machine, I want to debug a C++ application.
I make a debug build by adding -DCMAKE_BUILD_TYPE=Debug argument to the CMAKE part of the build settings. I set a breakpoint and I start debugging. The breakpoint is hit, but instead of stepping through the code linearly, the program counter (PC) keeps jumping around like it I was trying to debug optimized code, yet it's a debug build. The program is multi-threaded but I've verified that while debugging I am in the same thread, and yet the PC keep jumping to lines unrelated to the code.
Why could this happen? how to avoid it?
I suspect if this behavior may be related to another question I made a while ago debugging with gdb. Unfortunately, the question went unanswered and I'm not sure why this happens.
Related
I have a program that I have written in C++ under linux (Ubuntu 10.10).
The programming and debugging worked perfectly until the moment I added the following lines to the code:
mapfile = fopen(map_filename,"wb");
fwrite(map_header,1,20,mapfile); // <-- this is the problem line
fclose(mapfile);
After I added those, the program compiles ok, but the debugger now won't start. It immediately fails with this message:
Program completed, Exit code 0x177
error while loading shared libraries: unexpected PLT reloc type 0xcc
And if I remove the line with the "fwrite", the debugger will start normally.
This problem only happends inside Netbeans.
When I debug it using the command-line "gdb" it also works ok without any problems.
Anyone have idea why its happening and how to fix it?
P.S: Those problems started recently so I assume maybe it has to do something with system updates, I'm not sure.
Found the problem:
Not long ago, I removed some old C++ projects from netbeans. It figures out that netbeans (at least v7.0) remembers all the breakpoints that I put on old projects that don't even exist in the IDE anymore.
I found this by looking at the Debugger Console (Window->Debugging->Debugging Console) and seeing that when "gdb" starts, it tries to setup all these breakpoints from other projects or from projects that do not exists (this is a bug in netbeans, btw)
The solution: I simply cleaned all the breakpoints (inside Window->Debugging->Breakpoints) and now the program can be debugged properly.
Hope this will help to anyone out there who has the similar problem.
So, I have no idea why, but breakpoints in my code::blocks project are no longer working. I'm using MinGW-W64 compiler and GDB. I used to be able to use breakpoints, but now, for some reason, when I add them to my code they do absolutely nothing - code execution goes right past them without stopping.
Why might this be happening?
You might be compiling your code in release mode. Try changing it to debug mode. Checkout http://wiki.codeblocks.org/index.php?title=Debugging_with_Code::Blocks on how to turn on debugging symbols.
There are a number of errors going on here but I'm sure they are all linked, so first off I'm getting Access violation reading location exceptions at locations (generally near 0x00000000)
but I only get these exceptions in release and not in debug, even if i setup debugging to do so. Also I found where the error happens but when I step over that it goes in to a complete unrelated function that is not called in the line or in any of the functions in that line of code. But when similar code is called it still goes to this unrelated function but doesn't fail. This all only happens in release versions. I know which piece of code is causing the error as if I comment it out its all fine. Also in the watch window in release all the numbers are wrong most of the time, which has never been a problem but it could help also a added some code to it to output the values of variables to a file and the variables are all fine, the pointers are sensible, but when the exception happens it always says their 0x00000020 but when I look at the log they are fine. This is in 32 bit , but on 64 bit windows 7 in c++. Please any help would be good!
Visual Studio's debugger will cause the program to use a debug heap that can hide uninitialized memory if you use the option "Start with Debugging" to start your program, in release or debug. You can try to run your program built in the Debug configuration without the debugger attached, and then use the Attach to Process... option in the debug menu to attach to your executable.
If this doesn't help, I recommend using windbg to debug your program. For help getting started with windbg, take a look at the answers on this question.
Once windbg is configured and symbol paths are set up, you can use the "!analyze -v" option once the program crashes to get a lot of information about the crash automatically.
I encountered following problem:
I write program in c++ using VS2010. Debug build works properly when run with/without debugging in VS. When I launch built executable directly it also works.
Release build works when run with debugging in VS and alsp when I launch build executable directly.
Unfortunately, program does not work when I run release build in VS -without debugging-. Window is created and then program crashes quickly (without any error message). Since it crashes when run without debugging I don't know how to identify what causes the problem.
Any ideas what might be causing this? Thanks :)
It seems most likely you have some sort of memory error/corruption that just happens to work ok in the debugger.
You can try using couts to isolate how far/where it dies, or try a tool like Purify (or valgrind for free if you can port to Linux).
I left a program running last night, it worked fine for about 5 hours and then one of its built-in self-diagnostic tests detected a problem and brought up a dialog box telling me the issue. The program was built with debug information (/Zi). Is it possible to somehow get the debugger started so I can examine the value of some variables within the program? Or is it too late?
You can attach the debugger to the running process:
Debug > Attach to Process...
Just open up the program's solution first.
Assuming you've still got the error dialog on the screen you can break into the program and work back up the call stack examining variables etc.
For the future crashes ... if you have windbg or Visual Studio Professional, you can debug crash dumps, even when program isn't running. It is quite useful sometimes. See "MiniDumpWriteDump" on MSDN for more info.
Other than that it is "Attach to process".
Professional edition of Visual Studio have Just-in-Time debugger, that will kick in as soon as anything crashes, even if MSVC wasn't running. It will also locate source code (if debug info and source code are available) and open/create solution for you.
There is an option in the Debug menu to attach the debugger to a running process, IIRC.