Question

I have a simple question here. Is there a difference between passing a variable by reference in a function parameter like:

function do_stuff(&$a)
{
    // do stuff here...
}

and do it inside the function like:

function do_stuff($a)
{
    $var = &$a;
    // do stuff here...
}

What are the differences (if any) between using these two?. Also, can anybody give me a good tutorial that explains passing by reference? I can’t seem to grasp this concept 100%.

Thank you

Answer 1

Here’s a set of examples so you can see what happens with each of your questions.
I also added a third function which combines both of your questions because it will also produce a different result.

function do_stuff(&$a)
{
    $a = 5;
}

function do_stuff2($a)
{
    $var = &$a;
    $var = 3;
}

function do_stuff3(&$a)
{
    $var = &$a;
    $var = 3;
}

$a = 2;
do_stuff($a);
echo $a;
echo '<br />';

$a = 2;
do_stuff2($a);
echo $a;
echo '<br />';

$a = 2;
do_stuff3($a);
echo $a;
echo '<br />';