Question

Are 2 and 3 boxing/unboxing examples?

1) The documentation example:

int i = 123;
object iBoxed = i;
i = (int) iBoxed;

2: Is the boxing/unboxing as well?

int i = 123;
object iBoxed = i;
i = Int32.Parse(iBoxed.ToString());

3: Is the boxing/unboxing as well?

int i = 123;
object iBoxed = i;
i = Convert.ToInt32(iBoxed);

I assume that in all examples technically happens the same.

1. A value type is created on the stack
2. A reference is created on the stack, the value is copied to the heap.
3. The heap value is copied to the reference. The reference gets deleted.

So I guess 2 und 3 are examples for boxing/unboxing?

Answer 1

In all three examples:

iBoxed is a boxed copy of i.

In example 2:
There is no unboxing involved here, as ToString is a virtual method that will finally resolve to int.ToString, which will then be parsed by int.Parse, returning a non-boxed int on the stack.

In example 3:
iBoxed will get unboxed in the body of the method Convert.ToInt32 and returned as a non-boxed integer, on the stack again.