The point of these examples is to show how an object oriented
programming style could be used in C.  We start with a tiny example
in Java.  Our goal is to produce C code that feels  the same as the
Java code.

The example describes classes Point and Vector.  You can add a vector
to a point.  A basic design decision in both languages is whether doing
so modifies the point or creates a new point that is the result of the addition.
Directory "javaVersion" does the former, "javaVersionImmutable" the
latter.

The "cVersion" code represents objects as structs.  This lets you
create the actual object on the stack, something Java never does.
It lets you pass by value, which again doesn't conform to Java
semantics, and so is a bit unfamiliar.  On the other hand, C has
return by value, which turns out to be very handy if you want
what we're calling immutable Points.

The "cVersionPtrs" typedef's the classes to pointers.  That ends up
allowing code that feels a lot more Java-like.  At the same time,
because C has no garbage collection, it imposes a burden on the
C programmer that the Java programmer doesn't have to bear.
One example is that it can be difficult to make chained operations
on an object work.