Question

I try to pass a structure as a parameter.

Global structure:

struct ThreadParams 
 {
  HWND window;
  LIB::ServiceContainer* mrt;
 };

In the main thread:

ThreadParams threadparams;
threadparams.window = (HWND) GetSafeHwnd();
threadparams.mrt = m_rt;

CWinThread* pthread1;
pthread1 = (CWinThread*) AfxBeginThread(Thread1,(LPVOID)&threadparams,THREAD_PRIORITY_NORMAL,0,0,0);

Outside the class:

UINT Thread1(LPVOID lp)
{
 ThreadParams* threadparams = (ThreadParams*) lp;

     HWND hmainWindow = threadparams->window; 
 LIB::ServiceContainer* m_rt = threadparams->mrt;

}

Although it compiles fine, I get an error at runtime (it is an unexpected error) and I guess that I mess up with the pointer m_rt. Do you see any obvious mistakes?

Answer 1

ThreadParams threadparams;

Note that if it is a local variable, and the function which declares it returns after creating the thread, then the thread refers to an object which doesn’t exist anymore, as the local variable gets destroyed when the function returns. If that is the case, then create a new instance using new instead as:

ThreadParams * pthreadparams = new ThreadParams();

and pass it to the thread, so that it will exist even if the function which creates the thread returns. Of course, when you’re done with it, you’ve to delete it manually.