3v4l.org

run code in 300+ PHP versions simultaneously
<?php $cdate=date('2015-06-20'); $weekno = date('W',strtotime($cdate)); $yr = date('Y',strtotime($cdate)); $dt = $yr."W".$weekno ; echo date('Y-m-d',strtotime( $dt)); $dtt=strtotime("+6 days", strtotime($dt)); echo date('Y-m-d', $dtt); ?>
Output for 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.38, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
2015-06-152015-06-21
Output for 5.0.0 - 5.0.5
2015-01-092015-01-15
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9
1970-01-011970-01-07

preferences:
355.39 ms | 402 KiB | 453 Q