Re: Boolean type forced on string assignment inside if statement
| From: | Volmar Machado | Date: | Thu, 03 Jan 2013 18:11:35 +0000 |
| Subject: | Re: Boolean type forced on string assignment inside if statement | ||
| References: | 1 2 3 4 5 6 7 8 9 10 | Groups: | php.general |
| Request: | Send a blank email to php-general+get-320016@lists.php.net to get a copy of this message | ||
2013/1/3 Marc Guay <marc.guay@gmail.com>:
> I received the message below addressed only to me, but I believe the
> group could benefit. It looks like the single pipe is a bitwise
> operator so you will get an integer as a result (and probably other
> weird things to discover when using it on non-numbers).
>
> http://php.net/manual/en/language.operators.bitwise.php
>
>
> ---------- Forwarded message ----------
> From: Volmar Machado <qi.volmar@gmail.com>
> Date: 3 January 2013 12:42
> Subject: Re: [PHP] Boolean type forced on string assignment inside if statement
> To: Marc Guay <marc.guay@gmail.com>
>
>
> My results in a simple test:
>
> <?php
> $a = true;
> $b = false; // either null, or 0
> echo ('($a | $b))' . ($a | $b) . '<br>'); //1
> echo ('($a || $b))' . ($a || $b) . '<br>'); //1
> echo ('($b | $a)' . ($b | $a) . '<br>'); //1
> echo ('($b || $a)' . ($b || $a) . '<br>'); //1
> echo ('($a | $a)'. ($a | $a) . '<br>'); //1
> echo ('($a || $a)' . ($a || $a) . '<br>'); //1
> echo ('($b | $b)' . ($b | $b) . '<br>'); //0
> echo ('($b || $b)' . ($b || $b) . '<br>'); //false(outputs nothing)
> ?>
The basic difference for another test, where conditions are both true are :
<?php
$a = 4;
$b = 3;
echo ('($a | $b))' . ($a | $b) . '<br>'); //7
echo ('($a || $b))' . ($a || $b) . '<br>'); //1
echo ('($b | $a)' . ($b | $a) . '<br>'); //7
echo ('($b || $a)' . ($b || $a) . '<br>'); //1
echo ('($a | $a)'. ($a | $a) . '<br>'); //4
echo ('($a || $a)' . ($a || $a) . '<br>'); //1
echo ('($b | $b)' . ($b | $b) . '<br>'); //3
echo ('($b || $b)' . ($b || $b) . '<br>'); //1
echo ('($a & $b))' . ($a & $b) . '<br>'); //0
<-------------------------------------------
echo ('($a && $b))' . ($a && $b) . '<br>'); //1
echo ('($b & $a)' . ($b & $a) . '<br>'); //0
<-------------------------------------------
echo ('($b && $a)' . ($b && $a) . '<br>'); //1
echo ('($a & $a)'. ($a & $a) . '<br>'); //4
echo ('($a && $a)' . ($a && $a) . '<br>'); //1
echo ('($b & $b)' . ($b & $b) . '<br>'); //3
echo ('($b && $b)' . ($b && $b) . '<br>'); //1
?>
<?php
$a = 2;
$b = 3;
echo ('($a | $b))' . ($a | $b) . '<br>'); //3
echo ('($a || $b))' . ($a || $b) . '<br>'); //1
echo ('($b | $a)' . ($b | $a) . '<br>'); //3
echo ('($b || $a)' . ($b || $a) . '<br>'); //1
echo ('($a | $a)'. ($a | $a) . '<br>'); //2
echo ('($a || $a)' . ($a || $a) . '<br>'); //1
echo ('($b | $b)' . ($b | $b) . '<br>'); //3
echo ('($b || $b)' . ($b || $b) . '<br>'); //1
echo ('($a & $b))' . ($a & $b) . '<br>'); //2
<----------------------------
echo ('($a && $b))' . ($a && $b) . '<br>'); //1
echo ('($b & $a)' . ($b & $a) . '<br>'); //2
<-----------------------------
echo ('($b && $a)' . ($b && $a) . '<br>'); //1
echo ('($a & $a)'. ($a & $a) . '<br>'); //2
echo ('($a && $a)' . ($a && $a) . '<br>'); //1
echo ('($b & $b)' . ($b & $b) . '<br>'); //3
echo ('($b && $b)' . ($b && $b) . '<br>'); //1
?>
When the one of the operators were 2, the cases with "<------------"
returns 2 otherwise returns 0 (Or 1 when any operator is 1). And if
the operators are 1 and 2, return 0 too. Its curious for me.