Posted by Steve on 09/24/07 20:29

"Joe" <joe@faceh.com> wrote in message
news:1190663828.772978.15800@22g2000hsm.googlegroups.com...
>I am just starting to use Object Oriented PHP coding, and I am seeing
> quite often the following (this example taken from a wiki):
>
> $wakka =& new Wakka($wakkaConfig);
>
> What exactly is the =&, and why is it different from = ?

well, better syntax would have helped. it should read ' $something =
&$variable'. in this context, & means 'a reference to the memory location
where the value is stored'. without the &, it means 'a copy of the value of
the variable'.

clear as mud? rather than explain memory, let me have you do this:

$variable = 'hello';
$reference = &$variable;
$variable = 'world';
echo '<pre>' . print_r($reference, true) . '</pre>';
$reference = 'good-bye';
echo '<pre>' . print_r($variable, true) . '</pre>';

unset($variable);
unset($reference);

$variable = 'hello';
$reference = $variable;
$variable = 'world';
echo '<pre>' . print_r($reference, true) . '</pre>';
$reference = 'good-bye';
echo '<pre>' . print_r($variable, true) . '</pre>';

the first example, BY REFERENCE, means that both $variable and $reference
point to the same memory location. changing one but using the other makes no
difference - using either will have the same effect.

the second, BY VALUE, means that each variable points to two different
locations in memory. the only time they will be equal is when setting them
so. once you modify one of them, you have done so idependently of the
other - changing one has no effect on the other.

hope that makes more sense.

[Back to original message]