How to get year-sensitive calendar week ? date(“W”) gives back 52 for 1st of January

Question

As the headline says, PHP\'s date(\"W\") function gives back the calendar week (for the current day). Unfortunatly it gives back 52 or 53 for the first day(s) of most years.

Answer 1

$d = new DateTime('first monday january '.date('Y'));
echo $d->format("W");