How to create multiplethreads each with different ThreadProc() function using CreateThread()?

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I have successfully created a single thread using CreateThread().

Now I want to create 'n' number of threads but each with a different ThreadProc().

I have tried the following code but using it, 'n' number of threads are created all performing the same task (since Threadproc() function af all threads is same.)

    //Start the threads
for (int i=1; i<= max_number; i++) 
{
CreateThread( NULL, //Choose default security
              0, //Default stack size
              (LPTHREAD_START_ROUTINE)&ThreadProc,
              //Routine to execute. I want this routine to be different each time as I want each  thread to perform a different functionality.
              (LPVOID) &i, //Thread parameter
              0, //Immediately run the thread
              &dwThreadId //Thread Id
            ) 
}

Is there any way I can create 'n' number of Threads each with a different Thread procedure?

Posted 1-May-13 20:15pm

ayesha hassan

Updated 1-May-13 20:51pm

v2

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jsolutions_uk · Answer 1 · 2013-05-01T21:14:00

How about something along the lines of:

C++

typedef std::vector<LPTHREAD_START_ROUTINE> ThreadProcList;
typedef std::vector<DWORD> ThreadIdList;


ThreadProcList threadProcs;
ThreadIdList threadIds;


// add all the thread procs to threadProcs:
// threadProcs.pushBack((LPTHREAD_START_ROUTINE)&ThreadProc);

ThreadProcList::iterator end = threadProcs.end();
for(ThreadProcList::iterator it = threadProcs.begin();
    it != end; ++it) 
{
    DWORD threadId;
    ::CreateThread( NULL, 0, 
        *it,
         NULL, 0, &threadId);

    threadIds.push_back(threadId);
}

// Do whatever you want to do with threads

Jochen Arndt · Answer 2 · 2013-05-01T21:25:00

You may create an array holding the addresses of your thread procedures:

C++

LPTHREAD_START_ROUTINE pThreadProcs[] = { ThreadProc1, ThreadProc2 /*, ...*/};
for (int i = 0; i < sizeof(pThreadProcs) / sizeof(pThreadProcs[0]; i++)
{
    CreateThread(NULL, 0, pThreadProcs[i], (LPVOID)(i+1), 0 NULL);
}

Note also that I have passed the thread parameter by casting the value + 1 to LPVOID. The loop variable i is a local variable on the stack which address is no longer valid when all threads has been created. From within the threads use

C++

int i = (int)lpParameter

to get the value. If you pass a pointer to the parameter variable, you must ensure that the variable still exists when it is accessed by the thread.

CPallini · Answer 3 · 2013-05-01T21:46:00

Create an array of thread procedures, for instance:

C

DWORD WINAPI myThreadProcA(LPVOID  p)
{
	DWORD dw = (DWORD) p;
	return dw;
}
DWORD WINAPI myThreadProcB(LPVOID  p)
{
	DWORD dw = (DWORD)p;
	return dw*dw;
}


VOID CreateMyThreads(LPTHREAD_START_ROUTINE myProc[], int max_number, HANDLE hThread[])
{
	DWORD dwThreadId;

	for (int i=0; i< max_number; i++) 
	{
		hThread[i] = CreateThread( NULL, //Choose default security
              0, //Default stack size
              (LPTHREAD_START_ROUTINE)myProc[i],
              //Routine to execute. 
              (LPVOID) (i+1), //Thread parameter
              0, //Immediately run the thread
              &dwThreadId //Thread Id
            );
	}
}

Then you might call itm, for instance, this way:

C

const DWORD N=2;

HANDLE hThread[N];
DWORD dwExit[N];
LPTHREAD_START_ROUTINE myProc[N] = {myThreadProcA, myThreadProcB};

CreateMyThreads(myProc, N, hThread);

for (int i=0; i<N; i++)
{

 do
 {
     GetExitCodeThread(hThread[i], &dwExit[i]);
 } while (dwExit[i] ==  STILL_ACTIVE);

}

How to create multiplethreads each with different ThreadProc() function using CreateThread()?

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