How to obtain all the information of cell of a mesh?C++ ,MEDCOUPLING-9.11.0

I am a beginner in MEDCoupling and I would like to know how to obtain the composition information of cell of a 3D Unstructured mesh.
I already know which points make up a cell. But I don’t know how these points are connected into lines, nor do I know which faces make up the cell.
I couldn’t find an API to obtain the line equation, nor do I know the surface equation.