On 2011-05-04, harrismh777 <harrismh...@charter.net> wrote:
> Grant Edwards wrote:
>>> We do not consider passing a pointer as*by value* because its an
>>> > address; by definition, that is pass-by-reference.
>> No, it isn't. It's pass by value. The fact that you are passing a
>> value that is a pointer to another value is not relevent.
>>
>
> @ Edwards, &Schaathun
>
> You are most definitely mistaken.
The "pass by value" and "pass by reference" parameter passing
mechanisms are pretty well defined, and C uses "pass by value".
> I understand that semantically some people insist that when C
> receives parms as pointers that pass-by-reference is only being
> simulated.
And they are right.
> If I want to pass values to my C functions, I can. If I want to pass
> references to my C functions, I can.
We're not talking about what _you_ do. We're talking about what the C
_compiler_ does. The C compiler passes by value -- always.
> If I want to implement a C language that does not use pointers directly
> (hides them) I can implement pass by reference completely (on the
> surface).
That wouldn't be C.
> In fact, I can implement the C compiler so that pass by value is not
> allowed! [ it wouldn't look much like C, but its do-able ]
If you don't pass by value, it's not a C compiler.
> Everyone forgets that their high-level language is not 'really'
> what's working... gcc does not produce machine code... it produces
> assembler instructions that are passed to a translator... you can
> interrupt the process and have it produce the assembly instructions
> so you can see them if you want to... the point being, after all is
> said and done, all you can do with today's von Neumann processors is
> pass data directly (value) or indirectly (reference).
I have no idea what your point is.
At the machine level, there _is_ nothing but values. You can use a
value as an integer, or as a pointer. It's still just a value. But
we're talking about parameter passing mechanisms defined by high-level
language specifications -- particularly C.
--
Grant Edwards grant.b.edwards Yow! It was a JOKE!!
at Get it?? I was receiving
gmail.com messages from DAVID
LETTERMAN!! !
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