error LNK2005: _DllMain@12 already defined in MSVCRT.lib

Question

I am getting this linker error.

mfcs80.lib(dllmodul.obj) : error LNK2005: _DllMain@12 already defined in MSVCRT.lib(dllmain.obj)

Please tell me the correct way of eliminating this bug. I read solution on microsoft support site about this bug but it didnt helped much.

I am using VS 2005 with Platform SDK

Answer 1

If you're defining your own DllMain, in your project settigns you need to set 'Use of MFC' in the 'Configuration Properties/General' to 'Use Standard Windows Libraries'.

You should do a clean rebuild after changing it.

Answer 2

If you read the linker error thoroughly, and apply some knowledge, you may get there yourself:

The linker links a number of compiled objects and libraries together to get a binary.

Each object/library describes

• what symbols it expects to be present in other objects
• what symbols it defines

If two objects define the same symbol, you get exactly this linker error. In your case, both mfcs80.lib and MSVCRT.lib define the _DllMain@12 symbol.

Getting rid of the error:

1. find out which of both libraries you actually need
2. find out how to tell the linker not to use the other one (using e.g. the tip from James Hopkin)