CWinThread

A CWinThread object represents a thread of execution within an application. The main thread of execution is usually provided by an object derived from CWinApp; CWinApp is derived from CWinThread. Additional CWinThread objects allow multiple threads within a given application.

There are two general types of threads that CWinThread supports: worker threads and user-interface threads. Worker threads have no message pump: for example, a thread that performs background calculations in a spreadsheet application. User-interface threads have a message pump and process messages received from the system. CWinApp and classes derived from it are examples of user-interface threads. Other user-interface threads can also be derived directly from CWinThread.

Objects of class CWinThread typically exist for the duration of the thread. If you wish to modify this behavior, set m_bAutoDelete to FALSE.

The CWinThread class is necessary to make your code and MFC fully thread-safe. Thread-local data used by the framework to maintain thread-specific information is managed by CWinThread objects. Because of this dependence on CWinThread to handle thread-local data, any thread that uses MFC must be created by MFC. For example, a thread created by the run-time function cannot use any MFC APIs.

To create a thread, call AfxBeginThread. There are two forms, depending on whether you want a worker or user-interface thread. If you want a user-interface thread, pass to AfxBeginThread a pointer to the CRuntimeClass of your CWinThread-derived class. If you want to create a worker thread, pass to AfxBeginThread a pointer to the controlling function and the parameter to the controlling function. For both worker threads and user-interface threads, you can specify optional parameters that modify priority, stack size, creation flags, and security attributes. AfxBeginThread will return a pointer to your new CWinThread object.

Instead of calling AfxBeginThread, you can construct a CWinThread-derived object and then call CreateThread. This two-stage construction method is useful if you want to reuse the CWinThread object between successive creation and terminations of thread executions.

For more information on CWinThread, see the articles , , , and in Visual C++ Programmer’s Guide.

Class Members |  Base Class |  Hierarchy Chart

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See Also   CWinApp, CCmdTarget