Predefined Exceptions

PHP and SPL provide exception classes for common failure categories. Choose a type that communicates the failure, and catch exceptions only where the application can add context, recover, or translate the error.

Use This Reference When

• Throwing InvalidArgumentException for invalid caller input.
• Recognising runtime, logic, range, length, and out-of-bounds failures.
• Reviewing whether a broad catch (Throwable) belongs at an application boundary.

Report an Invalid Argument

<?php

function requirePositive(int $quantity): int
{
    if ($quantity < 1) {
        throw new InvalidArgumentException('Quantity must be positive.');
    }
    return $quantity;
}

echo requirePositive(2) . PHP_EOL;

// Prints:
// 2

Application-specific exception classes are still useful when callers need a domain-specific recovery path.