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Date: Thu, 15 Dec 2005 08:59:04 +0200 (EET)
Reply-To: Jani Taskinen <sniper@iki.fi>
To: Greg Beaver <greg@chiaraquartet.net>
cc: php-dev <internals@lists.php.net>
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Subject: Re: [PHP-DEV] why is '01' == '1.'?
From: sniper@iki.fi (Jani Taskinen)


     bool in_array ( mixed needle, array haystack [, bool strict] )

     See the last parameter? :)

     --Jani

On Wed, 14 Dec 2005, Greg Beaver wrote:

>
> Hi all,
>
> I realize that 1 == '01' and 1 == '1.', but why is this next code also
> bool(true)?
>
> <?php
> var_dump('1.' == '01');
> ?>
>
> In this case, a string is explicitly being compared to a string, and yet
> both are being converted to an int prior to comparison.  I can
> understand that implicit type conversion is needed when comparing
> strings to ints, but this can be dangerous.  phpDocumentor, for instance
> uses this code:
>
> if (in_array(substr($ltrimword, 0, 2), array('1.', '0.')))
>
> and assumes that it will only match either '1.' or '0.', but in fact, it
> will match '01', '1.', '0.', '00', and as such if this happens to be
> encountered, it can cause an infinite loop in phpDocumentor eating up
> all memory (bad - will be fixed in next release).
>
> Of course, I can fix this by using === for each element instead of
> in_array(), but this is extremely non-intuitive and dangerous behavior
> in the underlying PHP implementation.  The manual says nothing about
> auto-conversion of strings to ints when comparing two strings that
> satisfy is_numeric().  My question is whether this is a documentation or
> an internal PHP error?
>
> Greg