#include 
BOOL APIENTRY
DllMain
(
HMODULE hModule
,
DWORD  ul_reason_for_call
,
LPVOID lpReserved
)
{
switch
(
ul_reason_for_call
)
{
case
DLL_PROCESS_ATTACH
:
MessageBoxA
(
NULL
,
"Hello world!"
,
"MessageBoxA"
,
MB_OK
)
;
break
;
case
DLL_THREAD_ATTACH
:
case
DLL_THREAD_DETACH
:
case
DLL_PROCESS_DETACH
:
break
;
}
return
TRUE
;
}