3v4l.org

run code in 300+ PHP versions simultaneously
<?php $Start_Week = '201338'; $Optel_Week = 8; $Year_numbers= substr($Start_Week, 0, 4); $Week_numbers= substr($Start_Week, 4, 6); $Start_Week_berekend = date("YW", strtotime("{$Year_numbers}-W{$Week_numbers}+$Optel_Week week"));

preferences:
50.32 ms | 402 KiB | 5 Q