entry point required when building dll release on visual studio 2012

Question

I am new to DLL development and appreciated for any help.

I have an existing c++ project and am trying to build it into dll using visual studio 2012. I changed the target extension and configuration type to be dll. I also excluded my main function. When I rebuilt it, the compiler complains:

LINK : fatal error LNK1561: entry point must be defined

When I moved the main function back, I could build the project successfully.

I want to make a dll only because there are functions and objects I need to use for another project, so i don't think I need a main function for the dll. Is having a main function the only solution for this error? Thank you in advance.

Answer 1

Just like a program requires main , DLLs require DllMain , a place to start and handle loading and unloading of the DLL.

Rather than a DLL consider a static library . There is far less overhead, no DllMain and supporting loaders and unloaders, and they are built directly into the compiled executable so you don't have to carry an extra file around and run the risk of clients with out of date DLLs or some malicious tool replacing your DLL with theirs. If you don't need the ability to swap out the the library with a replacement, a DLL is probably overkill.