How can different PHP versions affect the implementation of date calculations in PHP scripts?

Different PHP versions can affect the implementation of date calculations in PHP scripts due to changes in the behavior of date functions or the handling of timezones. To ensure consistent results across different PHP versions, it is recommended to explicitly set the timezone before performing any date calculations.

// Set the timezone to ensure consistent date calculations
date_default_timezone_set('UTC');

// Perform date calculations
$today = date('Y-m-d');
$nextWeek = date('Y-m-d', strtotime('+1 week'));
echo "Today: $today\n";
echo "Next week: $nextWeek\n";