What are the key differences between PHP 5.6 and PHP 7.0 that could affect the functionality of a contact form script?

One key difference between PHP 5.6 and PHP 7.0 that could affect the functionality of a contact form script is the change in how errors are handled. PHP 7.0 introduced a new error handling system that is stricter than in PHP 5.6, which could lead to errors being displayed or logged differently. To ensure the contact form script works correctly in both PHP versions, it is important to update the error handling to comply with PHP 7.0 standards.

// Set error reporting level to display all errors in PHP 7.0
error_reporting(E_ALL);
ini_set('display_errors', 1);