【VB】操作系统调用 DllMain 函数的四种情况

VB 当操作系统调用 DllMain 函数的四种情况：

'当一个进程载入或卸载一个DLL时，DLLMAIN会被调用（DLLMAIN获得DLL_PROCESS_ATTACH消息），线程也是一样（获得DLL_THREAD_ATTACH消息）
Const DLL_PROCESS_ATTACH  As Long = 1                                           '当DLL被映射到进程的地址空间时
Const DLL_PROCESS_DETACH  As Long = 0                                           '当DLL被从进程的地址空间解除映射时
Const DLL_THREAD_ATTACH   As Long = 2                                           '当进程创建一线程时
Const DLL_THREAD_DETACH   As Long = 3                                           '当线程调用了 ExitThread 结束线程时
Public Function DllMain(ByVal hinstDLL As Long, ByVal fdwReason As Long, ByVal lpvReserved As Long) As Long 'Dll入口点函数
    Select Case fdwReason
        Case DLL_PROCESS_ATTACH
            '当DLL被映射到进程的地址空间时
        Case DLL_PROCESS_DETACH
            '当DLL被从进程的地址空间解除映射时
        Case DLL_THREAD_ATTACH
            '当进程创建一线程时
        Case DLL_THREAD_DETACH
            '当线程调用了 ExitThread 结束线程时
    End Select
    DllMain = 1
End Function

详见：VB DllMain DLL的进入,退出函数详解