To initialize non-MFC DLLs, your DLL source code must contain a function called DllMain. The following code presents a basic skeleton showing what the definition of DllMain might look like:

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BOOL APIENTRY DllMain(HANDLE hModule, DWORD ul_reason_for_call, LPVOID lpReserved) { switch( ul_reason_for_call ) { case DLL_PROCESS_ATTACH: ... case DLL_THREAD_ATTACH: ... case DLL_THREAD_DETACH: ... case DLL_PROCESS_DETACH: ... } return TRUE; }

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BOOL APIENTRY DllMain(HANDLE hModule, 
                      DWORD  ul_reason_for_call, 
                      LPVOID lpReserved)
{
    switch( ul_reason_for_call ) {
    case DLL_PROCESS_ATTACH:
    ...
    case DLL_THREAD_ATTACH:
    ...
    case DLL_THREAD_DETACH:
    ...
    case DLL_PROCESS_DETACH:
    ...
    }
    return TRUE;
}

Note
The Platform SDK documentation for DllEntryPoint says that the actual name of the entry-point function must be specified on the linker command-line with the /ENTRY option. With Visual C++, you do not need to use the /ENTRY option if the name of your entry-point function is DllMain. In fact, if you do use the /ENTRY option and name your entry-point function something other than DllMain, the C run-time library will not get initialized properly.

Note

The Platform SDK documentation for DllEntryPoint says that the actual name of the entry-point function must be specified on the linker command-line with the /ENTRY option. With Visual C++, you do not need to use the /ENTRY option if the name of your entry-point function is DllMain. In fact, if you do use the /ENTRY option and name your entry-point function something other than DllMain, the C run-time library will not get initialized properly.

What do you want to know more about?

The function specification for DllMain (Platform SDK)
Dynamic-link library entry-point function (Platform SDK)
The C run-time library behavior and _DllMainCRTStartup

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See Also

Concepts