<?php
function divide($a, $b) {
    if ($b === 0) {
        throw new Exception("Cannot divide by zero.");
    }
    return $a / $b;
}

try {
    echo divide(10, 2); // 5
    echo divide(10, 0); // throws
} catch (Exception $e) {
    echo "Error: " . $e->getMessage();
}
?>