Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:13628
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Message-ID: <41833298.6000906@prohost.org>
Date: Sat, 30 Oct 2004 02:20:08 -0400
User-Agent: Mozilla Thunderbird 0.8 (Windows/20040913)
MIME-Version: 1.0
To: Alan Knowles <alan@akbkhome.com>,  internals@lists.php.net
References: <418294D9.4070700@prohost.org> <4182E553.20801@akbkhome.com>
In-Reply-To: <4182E553.20801@akbkhome.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Subject: Re: [PHP-DEV] Negative string offset support
From: ilia@prohost.org (Ilia Alshanetsky)

While you are correct that invalid offset in a string will produce an 
error message. This error message is E_NOTICE, given that our default 
INI error reporting level won't display those it's arguable that very 
few people will see them and consequently do something about it.

 > echo $a{strlen($a)-1}; ? is that really that bad.

It is not that bad, but it could be better. Basic tests I've ran show 
that using a strlen() is 30-40% slower and substr() is 20-25% slower 
then $a{-1}.

Ilia

Alan Knowles wrote:

> 
> I do worry that at present
> $a = "a string";
> $p = 0
> while( $p < strlen($p) )
>   .. do stuff that could do $p-- or $p++ ....
>   echo $a{$p};
> }
> 
> at present that would produce a nice error if you went < 0.. easy to 
> spot.. - if -ve was supported it could do unexpected stuff..
> 
> Regards
> Alan
> 
> Ilia Alshanetsky wrote:
> 
>> I am wondering what are people's opinions on adding support for 
>> negative string offsets that could be used to access data from the end 
>> of a string.
>>
>> Ex. $a = "123"; echo $a[-1]; // would print 3
>>
>> I don't think we should do this for arrays, since -1 and similar are 
>> valid array keys, which means adding this support for arrays would 
>> break BC.
>>
>> Ilia
>>
>