Operator Null Coalescing

<?php
// Contoh 1
$name = "John Doe";
$username = $name ?? "Guest";
echo $username; // Output: John Doe

// Contoh 2
$score = null;
$finalScore = $score ?? 0;
echo $finalScore; // Output: 0

// Contoh 3
$city = null;
$defaultCity = "Unknown";
$selectedCity = $city ?? $defaultCity;
echo $selectedCity; // Output: Unknown

// Contoh 4
$language = "PHP";
$programmingLanguage = $language ?? "JavaScript";
echo $programmingLanguage; // Output: PHP
?>