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Having problems passing an object as param to CreateThread (C++)

Posted on 2010-08-23
Medium Priority
Last Modified: 2013-12-14

I'm having problems passing an object as param to CreateThread in C++. Any help greatly appreciated!!!

This is my Thread function, defined outside the class:
static DWORD WINAPI myThreadFunction(LPVOID param);

This is the class definition:
      public ref class MyClass : public MyParentClass

This is my CreateThread Call from within the MyClass object:
CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)myThreadFunction, this, 0, NULL);

error C2664: 'CreateThread' : cannot convert parameter 4 from 'MyClass::MyClass ^const ' to 'LPVOID'
1> No user-defined-conversion operator available, or
1> Cannot convert a managed type to an unmanaged type
Question by:php-newbie
  • 5
LVL 33

Expert Comment

ID: 33505006
Make it so:
CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)myThreadFunction, (LPVOID)this, 0, NULL);
LVL 33

Expert Comment

ID: 33505235
>>public ref class MyClass : public MyParentClass
It's managed code. Check this CodeProject article:
Managed threads in Managed C++

I hope it will give a bit different idea.
LVL 33

Expert Comment

ID: 33505259
One more:
Threads with Windows Forms Controls in Managed C++
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LVL 33

Expert Comment

ID: 33505295
Here is exactly same question in MSDN:
with an accepted answer and explanation.

Author Comment

ID: 33506939
Thanks for the info, pgnatyuk!

Let's say I go the route of creating a managed thread class as shown in this example:

How can I pass the 'this' pointer of MyClass (which creates the thread) to the Thread function?
Can I pass it in the definition and how would I do this?
Thread^ oThread = gcnew Thread( gcnew ThreadStart( &MyThread::myThreadFunction ) );


LVL 33

Accepted Solution

pgnatyuk earned 2000 total points
ID: 33507957
Almost. ParameterizedThreadStart should be used. It takes parameter of type object.
There is a simple example on this MSDN page.

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