When making changes to PHP files offline, what are the steps to ensure a smooth deployment on the server without encountering errors or security vulnerabilities?

When making changes to PHP files offline, it is important to follow best practices to ensure a smooth deployment on the server without encountering errors or security vulnerabilities. One way to achieve this is by thoroughly testing the changes on a local development environment before pushing them to the live server. Additionally, make sure to sanitize user input, validate data, and implement secure coding practices to prevent common security vulnerabilities like SQL injection or cross-site scripting attacks.

// Example of sanitizing user input in PHP
$user_input = $_POST['user_input'];
$sanitized_input = filter_var($user_input, FILTER_SANITIZE_STRING);