PHP Type Coversion Quiz

During an intake service review, why do senior engineers insist on casting incoming JSON fields to the expected types before passing them deeper into the application?

A warehouse script trims counts from labels. What does this snippet echo?

<?php
$value = '12cases';
echo (int) $value;
?>

Support compared these two lines. Why do they log different values?

<?php
echo '5' + 4;
echo '5' . 4;
?>

Strict audits flagged a comparison using ==. Why is === safer when checking user roles stored as strings?

A teammate wonders what FILTER_VALIDATE_INT returns. How does this snippet behave?

<?php
$result = filter_var('108', FILTER_VALIDATE_INT);
var_dump($result);
?>

During a design review, why do analysts recommend documenting expected array shapes using @var annotations such as @var array<int, string> $tags?

What does this optional parameter snippet echo for the fallback path?

<?php
$color = null;
$color ??= 'blue';
echo $color;
?>

A CLI importer wants to ensure a token contains only digits before casting. How does this snippet help?

<?php
echo ctype_digit('401A') ? 'ok' : 'reject';
?>

When converting stored booleans, why is it risky to rely on the truthiness of strings like "false" without casting?

New teammates compare json_decode outputs. What does this snippet display?

<?php
$payload = json_decode('{"active":true}', true);
var_dump($payload['active']);
?>

Why is number_format often used when showing floats to end users even though the internal value stays numeric?

A debugging session prints this snippet. What appears?

<?php
$value = 0.1 + 0.2;
echo (string) $value;
?>

Security reviews often forbid using == when comparing hashed tokens. Why?

A teammate checks how array_filter behaves with numeric strings. What prints?

<?php
$values = ['5', 5, '05'];
$filtered = array_filter($values, 'is_int');
print_r($filtered);
?>

When sanitizing query parameters, why is FILTER_SANITIZE_NUMBER_FLOAT with FILTER_FLAG_ALLOW_FRACTION useful?

A code sample shows the risk of loose comparisons. What does it echo?

<?php
var_dump(0 == '0e12345');
?>

Documentation for a typed DTO lists ?float $amount. What should reviewers infer from that declaration?

What does this typed property snippet print?

<?php
class Invoice {
    public int $units;
}
$invoice = new Invoice();
$invoice->units = '5';
echo $invoice->units;
?>

Why do reviewers prefer explicit (float) casting before dividing integers when precise decimals are required?

A teammate tests bool casting. What prints here?

<?php
echo (bool) "0" ? 'true' : 'false';
?>

Why is intval($value, 16) preferred over (int)$value when parsing hexadecimal IDs from hardware devices?

A logging helper shows the risk of settype. What prints?

<?php
$value = 'status';
settype($value, 'int');
var_dump($value);
?>

When migrating legacy bool columns stored as "Y" or "N", why is a conversion map (e.g., ["Y" => true, "N" => false]) clearer than casting?

What does this sprintf-based conversion output?

<?php
$amount = 5;
echo sprintf('%.2f', $amount);
?>

During QA, why is it important to distinguish between JSON null and the string "null" when decoding payloads?

An onboarding kata highlights strtotime conversion. What does this snippet echo?

<?php
echo (string) strtotime('2025-01-01 00:00:00');
?>

Why do developers avoid storing resources (like cURL handles) in session data when discussing type conversion?

A script compares integer input with a string reference. What prints?

<?php
$input = 10;
$reference = '10';
echo $input === $reference ? 'match' : 'mismatch';
?>

When integrating with older XML services, why is simplexml_load_string often cast to JSON and back before further processing?

Why does unpacking JSON into typed DTOs help with conversion discipline compared to using associative arrays everywhere?

In a migration guide, why must teams differentiate between (array) $object and iterator_to_array($object) when converting traversable data?

Why is floatval() sometimes favored over (float)$value during refactors?

A code review highlights bcadd usage. What type-related benefit does BCMath provide when summing currency as strings?

A utility guards against double casting. What is the outcome of this snippet?

<?php
$value = (int) (float) '12.9';
echo $value;
?>

Why is it valuable to log both the original value and its cast form during complex imports?