Lesson 18 of 20

Error Handling

Try-Catch and Custom Exceptions

PHP supports try-catch exception handling similar to other languages. PHP 8 added union types for catch blocks.

Example 
<?php
// Basic try-catch
try {
    $result = 10 / 0;
} catch (DivisionByZeroError $e) {
    echo 'Error: ' . $e->getMessage();
} finally {
    echo 'This always runs';
}

// Multiple catch types (PHP 8)
try {
    // risky code
} catch (InvalidArgumentException | RangeException $e) {
    echo 'Validation error: ' . $e->getMessage();
} catch (Exception $e) {
    echo 'General error: ' . $e->getMessage();
}

// Custom exception
class InsufficientFundsException extends RuntimeException {
    public function __construct(float $needed) {
        parent::__construct("Need $$needed more");
    }
}

function withdraw(float $amount, float $balance): float {
    if ($amount > $balance) {
        throw new InsufficientFundsException($amount - $balance);
    }
    return $balance - $amount;
}
?>