Question

I was trying to call a function that was allocated in the heap. After some failed attempts I tried the code in this website:

http://social.msdn.microsoft.com/forums/en-US/vcgeneral/thread/85d5da8c-edef-44b0-b42e-deb5f3eb2524

The code works flawlessly. It compiles, run, give the correct/expected result and finishes with no problem.

However if I try adding something like std::cout << “Hello World!” << std::endl in the function, copy it to the heap and then execute the heap function it just doesn’t work. If there’s a cout there it don’t work, without the cout it works.

I would like to know why this happens, and how can I solve this problem. Realize that I am doing this with the only purpose of learning, I have no interest in applying this to the practical usage.

If I the heap function calls a function that uses std::cout to print data, that code doesn’t work either.

Answer 1

Your problem lies with the fact that when you add the cout code to the function you essentially add some function calls. Microsoft C/C++ compiler uses some basic stack frame checking for detection of problems in runtime. Those checks are performed by calling the __RTC_CheckEsp function after each function call. The call to __RTC_CheckEsp uses the E8 opcode which means relative addressing. When the sample function is moved to the heap, the call to __RTC_CheckEsp becomes erroneous since it jumps to the wrong location.

Disable the runtime stack frame checking (in Visual Studio 2010): Project options -> Configuration Properties -> C/C++ -> Code Generation -> Basic Runtime Checks -> set it to Uninitialized Variables

Recompile. Run. Enjoy!