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

• lpParameter [in]
  The thread data passed to the function using the lpParameter parameter of the CreateThread, CreateRemoteThread, or CreateRemoteThreadEx function.

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

See also

CreateThread

CreateRemoteThread

CreateRemoteThreadEx

GetExitCodeThread