How Create my extern "C" for C++ and Matlab

Hi, I trying use a C++ dll in my matlab code, the information says I need an external C for use it, but I can not figure out how.

if  libisloaded('libjpeg')==false 
   addpath(fullfile(matlabroot,'wwp-data-sdk','lib-win'))
   addpath(fullfile(matlabroot,'wwp-data-sdk','headers'))
   addpath(fullfile(matlabroot,'wwp-data-sdk','headers','services'))
   addpath(fullfile(matlabroot,'wwp-data-sdk'))
end
loadlibrary('wwp-data-sdk.dll','center', 'alias','lib') 

I saw the links:

https://es.mathworks.com/matlabcentral/answers/45337-connecting-matlab-to-c-language-dll https://es.mathworks.com/matlabcentral/answers/56220-call-c-class-from-matlabhttps://es.mathworks.com/help/matlab/ref/loadlibrary.html