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Date: Sat, 12 Apr 2008 15:14:02 +0200
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To: Stefan Walk <stefan.walk@gmail.com>
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Subject: Re: [PHP-DEV] '1.8' == 1.8 can return false or yet another exampleof
 the uselessness of type juggling.
From: cschneid@cschneid.com (Christian Schneider)

Stefan Walk schrieb:
> Richard Quadling schrieb:
>> On 12/04/2008, Rasmus Lerdorf <rasmus@lerdorf.com> wrote:
>>> There is no bug here.  Please read:
>>>
>>>  http://docs.sun.com/source/806-3568/ncg_goldberg.html
>>>
>>>  -Rasmus
>>
>> So, would I be right in thinking that the only time type-juggling is
>> 100% successful is between strings and integers?
> 
> I suggest you read the page that Rasmus referred to. The effect has 
> nothing to do with type conversions, it happens with pure float 
> computations too.

For those curious about an example of this effect:
$a = 1.00001 + 0.79999;
$b = 1.8;
var_dump($a, $b, $a === $b);
=>
float(1.8)
float(1.8)
bool(true)

$a = 1.000001 + 0.799999;
$b = 1.8;
var_dump($a, $b, $a === $b);
=>
float(1.8)
float(1.8)
bool(false)

on my machine here.

- Chris