Using templates with arrays

[Zara]

I have been trying to substitute the macro that comes with the
compiler with the following template:

template <typename ITEM,size_t SIZE>
inline size_t arraySize(ITEM const (&array)[SIZE]) {
return SIZE;
}

AFAIK, it is compliant with the standard, and it should work.

In fact, it works perfectly on Borland C++ 2006, but it fails on GCC
3.4.1.

Should it work, from the Standard point of view, or am i missing
something?

Best regards,

Zara

[amparikh@gmail.com]

Re: Using templates with arrays


Zara wrote:

I have been trying to substitute the macro that comes with the
compiler with the following template:
>
template <typename ITEM,size_t SIZE>
inline size_t arraySize(ITEM const (&array)[SIZE]) {
return SIZE;
}
>
AFAIK, it is compliant with the standard, and it should work.
>
In fact, it works perfectly on Borland C++ 2006, but it fails on GCC
3.4.1.

The code is fine and it is a very common teqnique used for getting size
of an array.

>
Should it work, from the Standard point of view, or am i missing
something?
>
Best regards,
>
Zara

[Zara]

Re: Using templates with arrays

On Mon, 25 Sep 2006 06:06:52 +0200, Zara <me_zara@dea.sp amcon.org>
wrote:

>I have been trying to substitute the macro that comes with the
>compiler with the following template:
>
>template <typename ITEM,size_t SIZE>
inline size_t arraySize(ITEM const (&array)[SIZE]) {
return SIZE;
}

<..>

>In fact, it works perfectly on Borland C++ 2006, but it fails on GCC
>3.4.1.
>

So sorry for this comment, it works on both. The problem comes from
using an empty intilizer list for the array:

int data[]={};

This compiles on GCC and not on BCB, but after reading the relevant
part of C++Std, it should not compile (8.5.1-4 and footnote 91). My
fault.

Regrads,

Zara

[Rolf Magnus]

Re: Using templates with arrays

Zara wrote:

>>In fact, it works perfectly on Borland C++ 2006, but it fails on GCC
>>3.4.1.
>>

>
So sorry for this comment, it works on both. The problem comes from
using an empty intilizer list for the array:
>
int data[]={};
>
This compiles on GCC and not on BCB, but after reading the relevant
part of C++Std, it should not compile (8.5.1-4 and footnote 91).

My guess is that you forgot to turn on all the warning options for gcc.

[Zara]

Re: Using templates with arrays

On Mon, 25 Sep 2006 07:32:26 +0200, Rolf Magnus <ramagnus@t-online.de>
wrote:

>Zara wrote:
>

>>>In fact, it works perfectly on Borland C++ 2006, but it fails on GCC
>>>3.4.1.
>>>

>>
>So sorry for this comment, it works on both. The problem comes from
>using an empty intilizer list for the array:
>>
>int data[]={};
>>
>This compiles on GCC and not on BCB, but after reading the relevant
>part of C++Std, it should not compile (8.5.1-4 and footnote 91).

>
>My guess is that you forgot to turn on all the warning options for gcc.

[OT]
I do use:

-pedantic -pedantic-errors -Wall -Werror -std=c++98

It seems ther is no diagnostic for this error.

[OT]

[Rolf Magnus]

Re: Using templates with arrays

Zara wrote:

>>So sorry for this comment, it works on both. The problem comes from
>>using an empty intilizer list for the array:
>>>
>>int data[]={};
>>>
>>This compiles on GCC and not on BCB, but after reading the relevant
>>part of C++Std, it should not compile (8.5.1-4 and footnote 91).

>>
>>My guess is that you forgot to turn on all the warning options for gcc.

>
[OT]
I do use:
>
-pedantic -pedantic-errors -Wall -Werror -std=c++98
>
It seems ther is no diagnostic for this error.

Then it's the version. I'm using 4.1.2, and with -pedantic, it says:

error: zero-size array ‘data’

[OT]

[Marcus Kwok]

Re: Using templates with arrays

Zara <me_zara@dea.sp amcon.orgwrote:

I have been trying to substitute the macro that comes with the
compiler with the following template:
>
template <typename ITEM,size_t SIZE>
inline size_t arraySize(ITEM const (&array)[SIZE]) {
return SIZE;
}
>
AFAIK, it is compliant with the standard, and it should work.
>
In fact, it works perfectly on Borland C++ 2006, but it fails on GCC
3.4.1.
>
Should it work, from the Standard point of view, or am i missing
something?

I see you found that your problem was with a size-0 array, but this
article by Alf P. Steinbach has a couple other approaches, along with
their pro's and con's:

http://home.no.net/dubjai/win32cpptut/special/pointers/array_size.doc.pdf

--
Marcus Kwok
Replace 'invalid' with 'net' to reply