As far as I understand your comments, you need to use pre-processor directives in any hader file using to declare your function.
// in AnyHaderFile.h for FuncA() declaration
declspec(dllimport) void FuncA();
declspec(dllexport) void FuncA();
// in your DLL file, include it with after definition of _WITHINDLL_
// in your EXE file, you just need to include without _WITHINDLL_
In this particual case, the function is implemented in EXE (not in DLL unlike as usual).
I hope, I understand right.