Well, an object reference and a function name.

In this case (and not the examples which follow), it’s because Matt Mullenweg insists on maintaining compatibility with PHP4, despite the fact that support for PHP4 ended years ago.

$myArr = array (0 => “before change”);
foreach($myArr as &$element) {
$element = “after change”;
}
print_r($myArr);

First of all when you do something like:

$b = &$a;

You avoid arduous copying process which speeds up the whole program.

Another example is when you’re using “foreach” loop for working with arrays. If you apply some changes inside foreach loop to array’s values, the original array will not be modified, since what you have inside foreach loop is just the copy – so you’ll modify just the copy, not the original.

When you use & before particular array’s value to refference to the original – thus any change to the copy will also affect the original:

$myArr = array (0 => “before change”);
foreach($myArr as $id => &$element) {
$element[$id] = “after change”;
}
print_r($myArr);

When you print $myArr you’ll see “after change”. If you would you & before $element in the loop, like this:

foreach($myArr as $element)

You’d see the “before change” when you’d print the $myArr.
Hope I epxlained it well