Starting/Ending a Process

Hey everyone,

I'm working on a program in Visual C++ 2k8 and I've got a button that is responsible for creating and ending a thread. It's controlled by a switch statement that changes a boolean from true to false and depending on the value of the boolean, its going to start or a thread.

I'm using the function AfxBeginThread to start my thread, I'm just confused how to end it (how can I scan for the button being pressed again, or how do I stop the thread. I've been warned not to use AfxEndThread because it's somehow dangerous).

Any help will be greatly appreciated.

Thanks,

Matt

Start reading here: http://msdn2.microsoft.com/en-us/library/975t8ks0.aspx

gg

Thanks for the help codeplug,

MSDN is telling me to use AfxEndThread, however, it looks like there is no way to terminate an individual thread (I've got more than one running)...

Maybe I'm doing this all wrong...

I'll just say what I'm trying to do.

I'm making a program called AntiLeet, which monitors your keystrokes and scans them for phrases such as "lol" (these are defined in a file).

I've got one thread that constantly monitors the keys pressed, and puts them into a global vector called keys (25 last pressed keys).

The button activates and disables the scanner (which scans the pressed keys). I need to be able to disable/enable it because there will be variable changes.


Is there a way for a thread to access a variable when its running? (I'm new at this, sorry). Say, the thread has been running for a few seconds, but someone clicked a checkbox on a dialog box, is there a way to tell the thread this (or have it look it up)?

Thanks,

Matt

Don't confuse AfxEndThread with TerminateThread. TerminateThread is the dangerous one. Calling AfxEndThread is the same as just returning from the thread function.

One option is to use a CEvent to signal a thread to exit.

gg

When I call:

Code:

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AfxEndThread(0, true);

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The program terminates, and a debug window comes up.

Why?

I think that is difficult to say. A million things can go wrong.
Perhaps you try to be a little more specific as to what happen?
What kind of error do you get, for example?

Are you calling it inside one of the threads you created? Or are you calling it in the "main" thread of the application?

Calling AfxEndThread will end the current thread of execution.

gg

Quote:

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Originally Posted by Codeplug

Are you calling it inside one of the threads you created? Or are you calling it in the "main" thread of the application?

Calling AfxEndThread will end the current thread of execution.

gg

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That's it, I was calling it in the main program, which killed everything. Explains a lot...

For some reason, yesterday, nothing was making sence, if I just use a global and have the thread access that, everything works. Dont know why I didn't see that yesterday =\

Thanks for the help everyone :)

Quote:

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Originally Posted by guitarist809

For some reason, yesterday, nothing was making sence, if I just use a global and have the thread access that, everything works. Dont know why I didn't see that yesterday =\

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Wait. Are you saying two threads are using the same variable?
Have you used some kind of synchronization?

Quote:

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Originally Posted by Elysia

Wait. Are you saying two threads are using the same variable?
Have you used some kind of synchronization?

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I'm too noobish for synchronization. I looked at some of the MSDN example source code and said forget it.

using Afx threads is extremely easy, and the program works :)

Afx threads are threads. Threads are threads.
Are two threads accessing the same variable? If they do, then you need synchronization.

Quote:

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If they do, then you need synchronization.

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It is not so explicit... one can write (with atomic write) and second can read (with atomic read) - in this case - no locking is needed...

But that is one sort of synchronization. In a way, at least.
So an atomic operation, a critical section, a mutex, or something like that is needed to avoid race conditions.

Quote:

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atomic operation

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by atimic operation I mean here one assembler command... no lock is needed

if I have in one thread
flag = 1

and in the another
while(flag == 0)

I definitely do not want to add locking here

button states is the answer , look for the messages for buttons
switch(wParam)
{
case YOUR_BUTTON_ID:
}
why dont you use CreateThread as well ? , then you can have SuspendThread or TerminateThread