There is basically nothing you can do in C but can't do in C++; the overloading is basically syntactical sugar. In fact, there are things you can explicitly do in C but can't do in C++ (at least if you insist on doing them the "C++ way"). Example: as far as I know, C++ doesn't let you use virtual constructors; C can implement this through function pointers.

Of course, if you treat C++ as a superset of C and just do things "the C way" in cases when "the C++ way" doesn't work, obviously C++ can do everything C can.

The lack of an equivalent of offsetof in C++ is a real pity. This effectively prohibits using C-style data containers, whereby container's control data is embedded into the data instance itself. This sort of thing:

  struct record
  {
    int foo;
    int bar;
    ...

    list_item item; // keeps 'record' on some list
    tree_item item; // keeps 'record' on some tree
  };

There's no concise and memory-efficient way of doing the same in C++.

Boost.Intrusive: http://www.boost.org/doc/libs/1_35_0/doc/html/intrusive.html

> This seems to apply to just C++ actually.

why ? you can just as well create a cache of objects of a given type from within C, and use that for allocation/deallocation...

Well, you can replace malloc() and friends.