PHP Cookie Handling Essentials Quiz

During a login callback, why do reviewers insist on calling setcookie before echoing any template output or UTF-8 BOM?

A teammate captured this snippet after the controller finished processing. What does it echo?

<?php
    $result = setcookie('theme', 'dark', time() + 3600, '/');
    echo $result ? 'queued' : 'failed';
    ?>

Analytics wants to stuff tracking metadata into a single cookie. Why do architects cap each cookie at roughly 4 KB?

Given this request-scoped snippet, what is rendered?

<?php
    $_COOKIE['locale'] = 'fr-CA';
    echo $_COOKIE['locale'] ?? 'fallback';
    ?>

Why do browser vendors require the Secure flag whenever SameSite=None is used for cross-site flows?

Look at this diagnostic snippet executed during a request that already contains a feature cookie. What prints?

<?php
    $_COOKIE['feature'] = 'beta';
    setcookie('feature', 'stable', time() + 3600);
    echo $_COOKIE['feature'];
    ?>

Product wants to keep structured preferences in one cookie. Why is storing a JSON string safer than serializing PHP objects directly?

An engineer tests immediate availability of a freshly set cookie. What does this snippet echo?

<?php
    setcookie('promo', 'BOGO', ['expires' => time() + 600, 'path' => '/deals']);
    echo isset($_COOKIE['promo']) ? 'present' : 'not yet';
    ?>

Why does setting the cookie domain to .acme.fm matter when multiple subdomains share authentication?

Security requested that every sensitive cookie be marked HttpOnly. What problem does that flag reduce?

A controller guards against template fragments that might have already flushed output. What does this diagnostic snippet echo when no output was sent yet?

<?php
    if (headers_sent()) {
        echo 'fallback';
    } else {
        setcookie('ab', 'A');
        echo 'queued';
    }
    ?>

Why do platform teams standardize cookie paths (for example, /app versus /) even when the app only uses one route today?

Why should sensitive cookie values (session IDs, CSRF secrets) never be logged verbatim even during debugging?

How does this snippet interpret a structured cookie string?

<?php
    $_COOKIE['prefs'] = 'lang=en&tz=utc';
    parse_str($_COOKIE['prefs'], $prefs);
    echo $prefs['lang'] ?? 'none';
    ?>

Why do teams avoid setting Secure=false on production cookies even for anonymous tracking?

During privacy reviews, why do architects forbid copying entire user profiles into cookies for offline access?

A migration splits a large value into multiple cookie chunks for legacy browsers. What does this snippet print?

<?php
    $payload = str_repeat('x', 3000);
    $chunks = str_split($payload, 1000);
    foreach ($chunks as $index => $chunk) {
        setcookie('report_' . $index, $chunk, 0, '/');
    }
    echo count($chunks);
    ?>

Why do logout flows call setcookie with an expiration in the past as well as clearing server-side state?

Compliance asks for input validation on cookies before use. Which PHP API is most helpful for pulling a sanitized value?

How many seats does this snippet report when the cookie arrives as a numeric string?

<?php
    $_COOKIE['seats'] = '12';
    echo (int) $_COOKIE['seats'] + 3;
    ?>

Why might a shared domain leave the cookie domain attribute blank even when subdomains exist?

Frameworks often wrap setcookie inside response objects. Why do they still expose low-level cookie option maps?

What does this snippet output after decoding a JSON preference cookie?

<?php
    $_COOKIE['ui'] = '{"density":"compact","color":"midnight"}';
    $prefs = json_decode($_COOKIE['ui'], true);
    echo $prefs['color'] ?? 'default';
    ?>

Why do internationalized sites store only a locale code in cookies instead of the entire translation catalog?

Support asks whether to use expires or max-age when setting cookies. Why do many teams prefer max-age when supported?

How does this snippet validate numeric cookies before use?

<?php
    $_COOKIE['cart_qty'] = '7';
    $qty = filter_var($_COOKIE['cart_qty'], FILTER_VALIDATE_INT);
    echo $qty === false ? 'invalid' : $qty;
    ?>

Why should CSRF tokens live in HttpOnly, same-site cookies instead of JavaScript-accessible storage?

A product surface posts forms back to the same domain. Why is SameSite=Lax usually acceptable for its session cookie?

Why do security guides recommend hashing remember-me tokens before storing them in cookies?

A middleware signs cookie values to detect tampering. What does this snippet echo?

<?php
    $secret = 'build-2025';
    $_COOKIE['state'] = 'page=pricing';
    $signature = hash_hmac('sha256', $_COOKIE['state'], $secret);
    echo strlen($signature);
    ?>

Why do logout pages often clear both authentication and auxiliary personalization cookies?

When would setrawcookie be preferred over setcookie for the same value?

Why do multi-region platforms document cookie behavior per environment (staging, EU, US) even when code is shared?

Why should teams monitor response headers after CDN or WAF changes?

Why do incident responders keep a playbook for clearing or rotating cookies after breaches?