How can one ensure a smooth transition from PHP 5.6 to PHP 8.0 for a website?

To ensure a smooth transition from PHP 5.6 to PHP 8.0 for a website, one should first update the codebase to be compatible with PHP 7.x versions, as PHP 8.0 is not backward compatible with PHP 5.6. This involves fixing deprecated features, using strict typing, updating syntax, and ensuring compatibility with new features introduced in PHP 7.x. Once the codebase is updated to PHP 7.x standards, it can then be further optimized for PHP 8.0 by taking advantage of new features and improvements.

// Example code snippet for updating PHP codebase to be compatible with PHP 7.x

// Before PHP 7.x
$sum = array_sum(array(1, 2, 3));

// After PHP 7.x
$sum = array_sum([1, 2, 3]);