C/C++ Struct vs Class

Question

After finishing my C++ class it seemed to me the structs/classes are virtually identical except with a few minor differences.

I've never programmed in C before; but I do know that it has structs. In C is it possible to inherit other structs and set a modifier of public/private?

If you can do this in regular C why in the world do we need C++? What makes classes different from a struct?

Answer 1

In C++, structs and classes are pretty much the same; the only difference is that where access modifiers (for member variables, methods, and base classes) in classes default to private, access modifiers in structs default to public.

However, in C, a struct is just an aggregate collection of (public) data, and has no other class-like features: no methods, no constructor, no base classes, etc. Although C++ inherited the keyword, it extended the semantics. (This, however, is why things default to public in structs—a struct written like a C struct behaves like one.)

While it's possible to fake some OOP in C—for instance, defining functions which all take a pointer to a struct as their first parameter, or occasionally coercing structs with the same first few fields to be "sub/superclasses"—it's always sort of bolted on, and isn't really part of the language.