Re: [PHP] Overwrite value of true or false in PHP

[Bobby Pejman]

I see what's going on now.  Because of the type conversion, I am writing my 
code such that my return codes are translated to a strict 1 or 0.  The idea of 
having anything other than '' or 0 translating to a true scares me a little but 
thanks for pointing out the === operator.  I had to rewrite a lot of code after 
discovering it.  Good times...

Thanks for clarifying everyone.
-----Original Message-----
From: Martin Scotta <martinsco...@gmail.com>

Date: Mon, 7 Sep 2009 16:43:59 
To: <bpej...@gmail.com>
Cc: <php-general@lists.php.net>
Subject: Re: [PHP] Overwrite value of true or false in PHP


On Mon, Sep 7, 2009 at 4:14 PM, Bobby Pejman <bpej...@gmail.com> wrote:

> Hi,
>
> I noticed that the following returns a 1.
>
> echo (1<2) ? True : False
>
> I was under the impression that true/false are of type boolean and not int.
>  But in php anything other than 0 translates to true, meaning a 1.  What I
> am trying to achieve is for a 1 to be a 1 and a true or false to be a true
> and false respectively and I do not want to put quotes around the word
> true/false either because then it is no longer a boolean but string.
>
> Is it possible to overwrite php's true/false and declare them as boolean?
>  You often see in C++, some use Define().
>
> Thanks.
>
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>
>
Yes *true* and *false* are booleans.
PHP convert natively different types to boolean in order to help write
sentences like this

if( $object )
{
    $object->something();
}

while( $data = mysql_fetch_assoc( $resource ) )
{
    print_r( $data );
}

But we you try to print a boolean variable PHP convert it to string: true
becomes '1' and false becomes ''. That's why you can't just echo a boolean
variable to see the value, but you can rely on var_dump to show this.

$bool = true;
echo $bool;
var_dump( $bool );

$bool =! $bool;
echo $bool;
var_dump( $bool );


As other languages PHP as an special operator for checking types while
comparing values.

$a = 'false';
$b = true;

var_dump(
   $a == $b, # <-- true
   $a === $b # <-- false
);

This happens because values are converted before comparison so, 'false'
becomes true.
PHP converts everything different to an empty string as *true*
This also affect any type of variable.


-- 
Martin Scotta