DWORD gThreadProc(LONG);
class a
{
public:
   void StartThread();
   DWORD ThreadProc();
...
}
void a::StartThread()
{
   DWORD gdwThreadId = 0;
   CreateThread(NULL,0,(LPTHREAD_START_ROUTINE)gThreadProc,this,0,&gdwThreadId);
}
DWORD gThreadProc(LONG lParam)
{
   a* pThis = (a*)lParam;
   return pThis->ThreadProc();
}

class A
{
    int b;
};

DWORD MyThread(LPVOID param);

A aa;
DWORD id;
CreateThread(NULL,NULL,MyThread,(LPVOID)&aa,NULL,&id);

//在线程里面
DWORD MyThread(LPVOID param)
{
    A *p = (A *)param;
    p->b = 5; //这里就可以直接使用类实例里面的变量了
    return 0;
}