What are the advantages and disadvantages of using a CSV file for storing postal code and city name data compared to using an external API in PHP forms?

Using a CSV file for storing postal code and city name data provides the advantage of offline access and no dependency on external APIs. However, it may lead to slower data retrieval and potential data inconsistency if the file is not regularly updated. On the other hand, using an external API ensures real-time data accuracy but requires an internet connection and may pose limitations on the number of API requests.

// Example PHP code snippet using an external API to retrieve city name based on postal code

$postal_code = $_POST['postal_code'];
$api_url = "https://api.example.com/citylookup?postal_code=" . $postal_code;

$response = file_get_contents($api_url);
$data = json_decode($response, true);

$city_name = $data['city'];

echo "The city for postal code $postal_code is $city_name";