PHP时区偏移量小时

I want to be able to set Timezone offset in hours like in select' options: -1, 0,+1,+2.. then apply it's value to php date. But it's a 1st time i work with date fn.

<?php
date_default_timezone_set('UTC');
echo date("l");
echo'</br>';
echo date("g").':';
echo date("i");
?>

Thank you in advance!

You can do like this:

date_default_timezone_set('UTC');

echo date("l");
echo'</br>';

//+1,-1,0....any value
echo date("g", strtotime("+1 hour")).':';
echo date("i");