Wrap C++ dll in Another C++ dll

There is no much difference when you call the exported function of a dll regardless whether you are calling from an exe or from another dll.

To call exported functions of a dll you have two options: explicit or implicit linking.

I think this MSDN Article[^] could be a good starting point for you.

I recommend you start with Implicit Linking[^]. You will need a header (h) file and an import library file (lib) of the dll you would like to link.

For example, you have a test.exe, dll1.dll and dll2.dll, that are linked like this:
test.exe->dll1.dll->dll2.dll. I believe the link between test.exe and dll1.dll is established (otherwise you wouldn't ask). So, to link dll1 with dll2 you need the h and lib file from dll2. For example you have dll2_exports.h and dll2.lib. In this case within a cpp file of your dll1 add this line:

#include "dll1_exports.h"

Then call the functions from dll2 as you would normally do.

In the link options of dll1 you would need to add a reference to your dll2.lib. Provided you use Visual Studio, Right click on project of "dll1" in the Solution Explorer and select Properties. Navigate to Linker->Input. In the Additional Dependencies type dll2.lib.

Now build dll1. It should now be linked with dll2