What steps should be taken to ensure a smooth transition to PHP 7.0 without causing disruptions to the website functionality?

To ensure a smooth transition to PHP 7.0 without causing disruptions to the website functionality, it is important to first check the compatibility of the current codebase with PHP 7.0. This can be done by using tools like PHP Compatibility Checker. Additionally, make necessary updates to deprecated functions and syntax to ensure they are compatible with PHP 7.0. Finally, thoroughly test the website after the transition to PHP 7.0 to catch any potential issues before they impact users.

// Example code snippet to update deprecated functions for PHP 7.0 compatibility
// Deprecated function: mysql_connect
// Updated function: mysqli_connect

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

// Deprecated function
//$conn = mysql_connect($servername, $username, $password);

// Updated function
$conn = mysqli_connect($servername, $username, $password, $dbname);

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