Exceptions & Error Handling

What you'll walk away with

Explain the PHP runtime and web behavior behind Exceptions & Error Handling
Test normal, boundary, invalid, and failure cases
Write secure and maintainable PHP

Catch failures only where the program can recover or translate them meaningfully.

Build a Complete Mental Model

Distinguish the Throwable hierarchy, warnings and notices, exceptions, and fatal failures through a logging and response policy. Catch specific failures, preserve causes and context, and return a safe response at the global boundary.

Apply It in Real PHP

Run and test an original Exceptions & Error Handling example with normal, boundary, invalid, and failure inputs, recording output, warnings, exceptions, and side effects.

After This Lesson

Explain the contract and security boundary of Exceptions & Error Handling
Run an original working example
Automate an invalid or failure case

php

<?php
declare(strict_types=1);
function divide(float $a, float $b): float {
    if ($b == 0.0) throw new InvalidArgumentException('zero divisor');
    return $a / $b;
}
try { echo divide(10, 2); } catch (InvalidArgumentException $e) {
    error_log($e->getMessage()); echo 'Invalid calculation';
}

You should see

Try It Yourself

Run and test an original Exceptions & Error Handling example with normal, boundary, invalid, and failure inputs, recording output, warnings, exceptions, and side effects.

Security and Common Mistake

Exposing stack traces or secrets in production responses leaks sensitive information.

PHP Language Reference — PHP Documentation Group

Easy traps

Exposing stack traces or secrets in production responses leaks sensitive information.
Assuming one sample output proves input, output, authorization, and every failure path are correct.

Hands-on Exercise

Run and test an original Exceptions & Error Handling example with normal, boundary, invalid, and failure inputs, recording output, warnings, exceptions, and side effects.

You'll know it worked when: 5