On Fri, Dec 11, 2015 at 09:01:19AM +0100, aitor_czr wrote:
> Hi Katolaz,
>
> Here you are an example of two arguments (x,y) passed by reference:

[cut]

>
> void func(int *x, int *y)
> {
> int k = *x;
> *x = *y;
> *y = k;
> }
>
> This is the output:
>
> i = 1 j = 2
> i = 2 j = 1
>

Dear Aitor,

as many have already explained, this is not passing by reference, but
passing by value. Then it happens that the value is a pointer and, as
I already said in a previous email, this is a mechanism which *mimics*
a pass-by-reference through a pass-by-value. This is not being
pedantic, but calling things with their name, and avoiding
confusion. Pass-by-reference is what is normally used in Java or in
C++ (in the latter case, you have to use the "&" qualifier in the
signature of a function/method to signalling the choice between
pass-by-value and pass-by-reference).

C is one of the few remaining languages which is consistent about
allowing only one of the many possible argument passing
mechanisms. And the mechanism chosen by C is pass-by-value. Fullstop.


> On 12/10/2015 06:33 PM, dng-request@??? wrote:
> >On Thu, Dec 10, 2015 at 05:00:58PM +0100, aitor_czr wrote:
> >>>No, Katolaz, passing by value and passing by reference exist in C,
> >>>at least in C99.
> >>>
> >Could you please give a pointer to the place where this feature is
> >documented in the ANSI C99 standard?
>
> Passing by value and passing by reference in ANSI C99 are documented
> in the following book:
>
> C - The Complete Reference (by Herbert Schildt)
>

Oh dear, that explains a lot. Shitty book, IMHO, quite inaccurate,
full of mistakes and misconceptions, among which pass-by-reference is
just one little example. If you want to get a serious introduction to
C, then you are better off with the classical Kernighan & Ritchie,
which covers only C90, though. A good, competent, and complete
introduction to C99 is given in "C in a Nutshell", Prinz & Crawford,
O'Really (2005). But don't expect an easy read through either of them.

The best advice I have ever received about C is that I must not just
buy "any" book about C and assume it is "the bible" or represents
accurately what C is or is not. Except that book is the K&R.

HND

KatolaZ

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[ Enzo Nicosia aka KatolaZ --- GLUG Catania -- Freaknet Medialab ]
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