PHP Convert Time from/to 12 Hour or 24 Hour

Simple way to convert time with PHP’s date and strtotime.

// 24-hour time to 12-hour time
$time_in_12_hour_format = date("g:i a", strtotime("13:30"));
echo $time_in_12_hour_format;

// 12-hour time to 24-hour time
$time_in_24_hour_format = date("H:i", strtotime("1:30 PM"));
echo $time_in_24_hour_format;