What is the function strtotime in PHP and how can it be used to calculate time differences?

The strtotime function in PHP is used to convert a date/time string into a Unix timestamp. This can be useful for calculating time differences between two dates or times. To calculate time differences, you can convert both dates into Unix timestamps using strtotime, subtract the timestamps, and then convert the result back into a readable format if needed.

$date1 = strtotime("2022-01-01 12:00:00");
$date2 = strtotime("2022-01-01 14:30:00");

$timeDifference = $date2 - $date1;

echo "Time difference: " . gmdate("H:i:s", $timeDifference);