Reference Parameters

A reference parameter can update the caller variable directly.

reference_parameters.php

<?php
function addPoints(int &$score, int $bonus): void {
    $score = $score + $bonus;
}

$score = ;
addPoints($score, 5);

echo "score=" . $score . "\n";

<?php
function addPoints(int &$score, int $bonus): void {
    $score = $score + $bonus;
}

$score = ;
addPoints($score, 5);

echo "score=" . $score . "\n";

<?php
function addPoints(int &$score, int $bonus): void {
    $score = $score + $bonus;
}

$score = ;
addPoints($score, 5);

echo "score=" . $score . "\n";

reference parameter An `&` before a parameter lets assignments inside the function update the caller's variable.