array to pointer decay question !!

[m sergei]

main(int argc, char *argv[])

the second parameter to function main takes a pointer to an array.

can we also write it in terms of a reference rather than a pointer ?
an example of using (usage) as a reference would be helpful

[Richard Bos]

Re: array to pointer decay question !!

sergei_m_1@yaho o.com (m sergei) wrote:
[color=blue]
> main(int argc, char *argv[])
>
> the second parameter to function main takes a pointer to an array.
>
> can we also write it in terms of a reference rather than a pointer ?[/color]

Of course not. References are C++, not C.

Perhaps you want comp.lang.c++?

Richard

[Thomas Matthews]

Re: array to pointer decay question !!

m sergei wrote:[color=blue]
> main(int argc, char *argv[])
>
> the second parameter to function main takes a pointer to an array.
>
> can we also write it in terms of a reference rather than a pointer ?
> an example of using (usage) as a reference would be helpful[/color]
No, references are C++.

You can declare it as: char * * arg_list.

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[Default User]

Re: array to pointer decay question !!

m sergei wrote:[color=blue]
>
> main(int argc, char *argv[])
>
> the second parameter to function main takes a pointer to an array.[/color]

No it doesn't. It takes a pointer to a pointer to char. That's why an
equivalent version is:

int main (int argc, char **argv)

[color=blue]
> can we also write it in terms of a reference rather than a pointer ?[/color]

Ask in comp.lang.c++ where they will tell you that it is not the same.




Brian Rodenborn

[Dan Pop]

Re: array to pointer decay question !!

In <40E2EA46.5C4B1 19C@boeing.com. invalid> Default User <first.last@boe ing.com.invalid > writes:
[color=blue]
>m sergei wrote:[color=green]
>>
>> main(int argc, char *argv[])
>>
>> the second parameter to function main takes a pointer to an array.[/color]
>
>No it doesn't. It takes a pointer to a pointer to char. That's why an
>equivalent version is:
>
>int main (int argc, char **argv)[/color]

However, the equivalent version is losing a semantic clue: that argv is
supposed to point to the first pointer of an array of pointers. It makes
no difference to the compiler, but it does make a difference to the
human reader.

Furthermore it is quite idiomatic to refer to a pointer to the first
element of an array as a pointer to an array, as long as it is clear that
its type is not pointer to array. Example from the C standard itself:

2 The strcpy function copies the string pointed to by s2 (including
the terminating null character) into the array pointed to by
^^^^^^^^^^^^^^^ ^^^^^^^^
s1. If copying takes place between objects that overlap, the
^^
behavior is undefined.

The case of main being so well known, most advanced programmers prefer
**argv because it is easier to type than *argv[]. However, in any other
function interface, I would recommend *argv[] instead of **argv, due to
the semantic clue I was talking above. It's much less of an issue when
dealing with plain arrays, so I wouldn't bother with a[] instead of *p.

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Dan.Pop@ifh.de

[Default User]

Re: array to pointer decay question !!

Dan Pop wrote:[color=blue]
>
> In <40E2EA46.5C4B1 19C@boeing.com. invalid> Default User <first.last@boe ing.com.invalid > writes:
>[color=green]
> >m sergei wrote:[color=darkred]
> >>
> >> main(int argc, char *argv[])
> >>
> >> the second parameter to function main takes a pointer to an array.[/color]
> >
> >No it doesn't. It takes a pointer to a pointer to char. That's why an
> >equivalent version is:
> >
> >int main (int argc, char **argv)[/color]
>
> However, the equivalent version is losing a semantic clue: that argv is
> supposed to point to the first pointer of an array of pointers. It makes
> no difference to the compiler, but it does make a difference to the
> human reader.[/color]

I agree with you there, I use the char *argv[] style.
[color=blue]
> Furthermore it is quite idiomatic to refer to a pointer to the first
> element of an array as a pointer to an array, as long as it is clear that
> its type is not pointer to array.[/color]

But when we're talking about equivalent types, the syntax is more
important than the semantics. If we were describing the usage of argv,
then you'd be correct. I don't agree with you regarding the OP's
question.




Brian Rodenborn

[Dan Pop]

Re: array to pointer decay question !!

In <40E318A0.CAAF9 458@boeing.com. invalid> Default User <first.last@boe ing.com.invalid > writes:
[color=blue]
>Dan Pop wrote:[color=green]
>>
>> In <40E2EA46.5C4B1 19C@boeing.com. invalid> Default User <first.last@boe ing.com.invalid > writes:
>>[color=darkred]
>> >m sergei wrote:
>> >>
>> >> main(int argc, char *argv[])
>> >>
>> >> the second parameter to function main takes a pointer to an array.
>> >
>> >No it doesn't. It takes a pointer to a pointer to char. That's why an
>> >equivalent version is:
>> >
>> >int main (int argc, char **argv)[/color]
>>
>> However, the equivalent version is losing a semantic clue: that argv is
>> supposed to point to the first pointer of an array of pointers. It makes
>> no difference to the compiler, but it does make a difference to the
>> human reader.[/color]
>
>I agree with you there, I use the char *argv[] style.
>[color=green]
>> Furthermore it is quite idiomatic to refer to a pointer to the first
>> element of an array as a pointer to an array, as long as it is clear that
>> its type is not pointer to array.[/color]
>
>But when we're talking about equivalent types, the syntax is more
>important than the semantics. If we were describing the usage of argv,
>then you'd be correct. I don't agree with you regarding the OP's
>question.[/color]

Then, you're not agreeing with the C standard itself, either, which uses
the same "sloppy" terminology, as I have shown in the part you have so
conveniently snipped from my post.

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Dan.Pop@ifh.de