Need software to help to understand C source code
I have downloaded a complete source code of network simulation. It was writed in C++ Object. I need to understand the structure and running mechanism of this code. The structure, I mean, is which objects inherit which objects. I need a object inheritance diagrams of the whole source code. The running mechanism is when the application runs, which functions is called first, and next .... Please suggest me such a software or a software to help me to understand the source code less painfully.