How can updates or theme changes in Wordpress impact PHP functionality?

Updates or theme changes in WordPress can impact PHP functionality if the code in the theme or plugins is not compatible with the updated version of WordPress. To solve this issue, it is important to regularly update themes, plugins, and WordPress core to ensure compatibility. Additionally, checking for any deprecated functions or hooks in the PHP code and updating them to their current equivalents can help prevent any issues with PHP functionality.

// Example code to update deprecated function in PHP
// Deprecated function: mysql_connect()
// Updated function: mysqli_connect()

$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

// Create connection
$conn = mysqli_connect($servername, $username, $password, $dbname);

// Check connection
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}
echo "Connected successfully";