How do you create and use custom exception classes in PHP? PHP में custom exception classes कैसे बनाएं और इस्तेमाल करें?

Create a class that extends Exception (or a more specific built-in subclass) to represent domain-specific error conditions with extra context.

class InsufficientFundsException extends Exception {
    public function __construct(
        private float $requested,
        private float $available
    ) {
        parent::__construct(
            "Requested {$requested} but only {$available} available"
        );
    }

    public function getShortfall(): float {
        return $this->requested - $this->available;
    }
}

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

try {
    withdraw(500, 200);
} catch (InsufficientFundsException $e) {
    echo $e->getMessage();
    echo 'Shortfall: ' . $e->getShortfall();
}

Interview tip: Point out that custom exceptions let you catch specific business errors separately from generic ones, and can carry structured data (like getShortfall() here) instead of just a string message.