How do I transfer parameter to each thread?

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In my VC++ code

CWinThread* Serial_Thread[3];

_tmain(int argc, char* argv[])
{

for(int i = 0 ; i < 3; i++)
{
Serial_Thread[i] = AfxBeginThread(SendSerial_Thread, &i);
}
}
and
static UINT SendSerial_Thread(LPVOID pParam)
{
int x = (int)pParam;
}

But when debugging,
the last x of thread is not equal of i of main program;
(if i=0, x=4060628....)

I thought it is simple.
But now, I don't know why or where is my fault....
Please let me know

Thank in advance.

What I have tried:

2 more hours wasted for this problem...

Posted 17-Jun-17 4:53am

Member 12330615

Updated 17-Jun-17 5:03am

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Richard MacCutchan · Accepted Answer · 2017-06-17T05:03:00

Solution 1

pParam is a pointer to int not an int. Should be

C++

static UINT SendSerial_Thread(LPVOID pParam)
{
    int x = *reinterpret_cast<PINT>(pParam);
}

Posted 17-Jun-17 5:03am

Richard MacCutchan

Comments

Member 12330615 18-Jun-17 22:13pm

After modifying according of your advice, and careful testing, I found testing almost applied. But sometimes x had same error....

Richard MacCutchan 19-Jun-17 4:41am

The variable x only exists within the for loop. So once that loop ends there is no guarantee that is will hold the expected value. In fact, once that loop ends the main thread may also end as it does not wait for any of the child threads to complete. You should use a variable (and a main thread) that will exist for the lifetime of all threads that may refer to it.