When is it good to use pass by reference in PHP?

Answers of > When is it good to use pass by reference in PHP?

If you are working on a very large array and w3coded php references plan on modifying it inside a function, you w3coded php references actually should use a reference to prevent it w3coded php references from getting copied, which can seriously w3coded php references decrease performance or even exhaust your memory w3coded php references limit. ,If it is avoidable though (that is small w3coded php references arrays or scalar values), I'd always use w3coded php references functional-style approach with no side-effects, w3coded php references because as soon as you pass something by w3coded php references reference, you can never be sure what passed w3coded php references variable may hold after the function call, which w3coded php references sometimes can lead to nasty and hard-to-find w3coded php references bugs.,In C++ if you pass a large array to a w3coded php references function, you need to pass it by reference, so w3coded php references that it is not copied to the new function w3coded php references wasting memory. If you don't want it modified w3coded php references you pass it by const reference. ,The following w3coded php references does not apply to objects, as it has been w3coded php references already stated here. Passing arrays and scalar w3coded php references values by reference will only save you memory if w3coded php references you plan on modifying the passed value, because w3coded php references PHP uses a copy-on-change (aka copy-on-write) w3coded php references policy. For example:

The following does not apply to objects, as it has been already stated here. Passing arrays and scalar values by reference will only save you memory if you plan on modifying the passed value, because PHP uses a copy-on-change (aka copy-on-write) policy. For example:

# $array will not be copied, because it is not modified.
function foo($array) {
    echo $array[0];
}

# $array will be copied, because it is modified.
function bar($array) {
    $array[0] += 1;
    echo $array[0] + $array[1];
}

# This is how bar shoudl've been implemented in the first place.
function baz($array) {
    $temp = $array[0] + 1;
    echo $temp + $array[1];
}


# This would also work (passing the array by reference), but has a serious 
#side-effect which you may not want, but $array is not copied here.
function foobar(&$array) {
    $array[0] += 1;
    echo $array[0] + $array[1];
}

Then what functionality does it provide? It gives you the ability to modify the variable in the calling scope:

class Bar {}
$bar = new Bar();

function by_val($o) { $o = null; }
function by_ref(&$o) { $o = null; }

by_val($bar); // $bar is still non null
by_ref($bar); // $bar is now null

Functions that look like this:

$foo = modify_me($foo);

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