Question

How to pass a variable by reference to a function in PHP

Answer 1

function swap(&$a, &$b) // use & in function argument &$a
{
    $tmp = $a;
    $a = $b;
    $b = $tmp;
}

$x = 4;
$y = 8;
swap($x, $y);

echo $x . " " . $y; // 8 4

/*
run:

8 4

*/

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Answer 2

function set_value(&$v)
{
    $v = $v * 3;
}

$n = 10;

set_value($n);

echo $n; // 30

/*
run:
 
30
 
*/

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