PHP return reference vs return value

In PHP, a function can either return a value in a way that creates a copy of it or returns a reference to it. The method of return can have an impact on how the returned value behaves.

Returning by value involves the creation of a copy of the original value. If a function returns a value by value, any modifications made to the returned value will not affect the original value. For instance:

function returnByValue($num) {
    return $num;
}

$original = 5;
$returned = returnByValue($original);
$returned = 10;

echo $original; // Output: 5

Here, the returnByValue function returns a copy of the argument $num, and any changes to the returned value will not affect the original value $original.

When a function returns a value by reference, a reference to the original value is returned, not a copy. In this case, any modifications to the returned value will also affect the original value. Here’s an example:

function &returnByReference($num) {
    return $num;
}

$original = 5;
$returned = &returnByReference($original);
$returned = 10;

echo $original; // Output: 10

Here, the returnByReference function returns a reference to the argument $num, and any modifications to the returned value will affect the original value $original.

It’s crucial to be cautious when using return by reference, as it can result in unexpected consequences if not used properly. In most cases, it’s recommended to use return by value unless there’s a specific requirement for return by reference.