Hi @Aliaksei.Kobylinskiy,

I believe the CoatingSample file shipped with OpticStudio is a C file: CoatingSample.c

If you are trying to convert it to a C++ file, it is necessary but not sufficent to change the extension to: CoatingSample.cpp

I don’t have time to thoroughly test, but I believe if you replace those lines (13-14) in the original file:

int __declspec(dllexport) APIENTRY UserObjectDefinition(double *data, double *tri_list);
int __declspec(dllexport) APIENTRY UserParamNames(char *data);

by the following lines:

extern "C" {
	int __declspec(dllexport) APIENTRY UserObjectDefinition(double* data, double* tri_list);
	int __declspec(dllexport) APIENTRY UserParamNames(char* data);
}

It should correct the issue. This can provide more information: https://stackoverflow.com/questions/1041866/what-is-the-effect-of-extern-c-in-c.

Please let us know otherwise.

Take care,

David