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ThreadProc callback function

An application-defined function that serves as the starting address for a thread. Specify this address when calling the CreateThread, CreateRemoteThread, or CreateRemoteThreadEx function.

The LPTHREAD_START_ROUTINE type defines a pointer to this callback function. ThreadProc is a placeholder for the application-defined function name.

Syntax

DWORD WINAPI ThreadProc(
  _In_ LPVOID lpParameter
);

Parameters

Return value

The return value indicates the success or failure of this function. The return value should never be set to STILL_ACTIVE (259), as noted in GetExitCodeThread.

Do not declare this callback function with a void return type and cast the function pointer to LPTHREAD_START_ROUTINE when creating the thread. Code that does this is common, but it can crash on 64-bit Windows.

Remarks

A process can determine when a thread it created has completed by using one of the wait functions. It can also obtain the return value of its ThreadProc by calling the GetExitCodeThread function.

Each thread receives a unique copy of the local variables of this function. Any static or global variables are shared by all threads in the process. To provide unique data to each thread using a global index, use thread local storage.

Examples

For an example, see Creating Threads.

Requirements

Minimum supported client

Windows XP [desktop apps only]

Minimum supported server

Windows Server 2003 [desktop apps only]

Header

WinBase.h on Windows XP, Windows Server 2003, Windows Vista, Windows 7, Windows Server 2008 and Windows Server 2008 R2 (include Windows.h); Processthreadsapi.h on Windows 8 and Windows Server 2012

See also

CreateThread

CreateRemoteThread

CreateRemoteThreadEx

GetExitCodeThread