PHP interviews cover language semantics, OOP, Laravel or Symfony, MySQL, and web security basics. Below are the most common questions with model answers. Junior: core theory, definitions, and simple practical cases.
== compares after type juggling, === compares value and type. PHP 8 made the juggling far saner — 0 == "foo" is now false — but the rule stands: use === unless you have a reason not to, because the comparison table is something nobody should have to remember.
An interface declares what a class can do and carries no implementation. An abstract class can hold state and partial implementation, and a class extends only one. A trait is code injected into a class — PHP's answer to not having multiple inheritance. Traits are for shared implementation, interfaces for shared contract.
public is reachable anywhere, protected from the class and its subclasses, private only from the declaring class. private is stricter than people expect — a subclass cannot see it. Default to private and widen when something outside genuinely needs access.
Both pull in a file; require raises a fatal error if it is missing, include only a warning and carries on. The _once variants skip a file already loaded. In modern code you meet these rarely, because Composer's autoloader resolves classes by namespace and you never write the path.
Composer resolves and installs dependencies. composer.json says what you want, composer.lock records exactly what was resolved — which is why the lock file is committed and why composer install on the server reproduces the same tree rather than picking newer versions.
PHP converting types to compare or operate on them. It still bites when a string from a form arrives where a number was expected, and in loose comparisons inside in_array or switch, which use == by default. Declaring strict_types=1 at the top of a file turns the quiet coercion into an error.
$_GET, $_POST, $_SERVER, $_SESSION and the rest hold request data. Reading them directly spreads unvalidated input through the code and makes anything that touches them untestable, since there is no request to construct. A framework's request object wraps them, which is why you use it.
In a real interview you speak under pressure. Cam asks these same questions, scores every answer, and shows exactly what to fix.
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