Challenge 2 — Solution

Task: Write a function validateRegistration($email, $age) that uses
filter_var() to check both, returning an array of error messages
(empty if everything is valid). Test it with one fully valid set of
inputs and one fully invalid set.

<?php
    function validateRegistration(string $email, string $age): array {
        $errors = [];

        if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
            $errors[] = "Please enter a valid email address.";
        }

        if (!filter_var($age, FILTER_VALIDATE_INT, ["options" => ["min_range" => 0, "max_range" => 130]])) {
            $errors[] = "Please enter a valid age.";
        }

        return $errors;
    }

    $validErrors = validateRegistration("sam@example.com", "28");
    $invalidErrors = validateRegistration("not-an-email", "999");

    echo "Valid input errors: " . count($validErrors) . "<br>";
    print_r($invalidErrors);
?>


Output:
Valid input errors: 0
Array
(
    [0] => Please enter a valid email address.
    [1] => Please enter a valid age.
)

Notes:
- validateRegistration("sam@example.com", "28") returns an empty array
  because both filter_var() checks pass - a correctly-formatted email
  and an age within the 0-130 range.
- validateRegistration("not-an-email", "999") fails both checks: the
  email has no @ symbol or valid domain shape, and 999 falls outside
  the max_range of 130, so both error messages end up in the returned
  array.
- Returning an array of messages (rather than just true/false) lets the
  calling code display every problem at once, rather than only the
  first one found - genuinely more helpful for a real registration form
  where a visitor benefits from seeing all their mistakes together.