3v4l.org

run code in 300+ PHP versions simultaneously
<?php $origin = mktime(18, 0, 0, 7, 31, 2015); var_dump( date('r', $origin), date('r', strtotime('-1 months', $origin)) );
Output for 4.3.11, 4.4.0 - 4.4.9, 5.0.4 - 5.0.5, 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 - 5.6.30, 7.0.0 - 7.0.30, 7.1.0 - 7.1.25, 7.2.0 - 7.2.33, 7.3.0 - 7.3.31, 7.4.0 - 7.4.33, 8.0.0 - 8.0.12, 8.0.14 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.19, 8.3.0 - 8.3.7
string(31) "Fri, 31 Jul 2015 18:00:00 +0200" string(31) "Wed, 01 Jul 2015 18:00:00 +0200"
Output for 7.3.32 - 7.3.33, 8.0.13
string(31) "Fri, 31 Jul 2015 18:00:00 +0000" string(31) "Wed, 01 Jul 2015 18:00:00 +0000"
Output for 4.3.0 - 4.3.10, 5.0.3
string(31) "Fri, 31 Jul 2015 18:00:00 +0200" string(31) "Wed, 1 Jul 2015 18:00:00 +0200"
Output for 5.0.0 - 5.0.2
string(31) "Fri, 31 Jul 2015 18:00:00 +0200" string(31) "Wed, 1 Jul 2015 00:00:00 +0200"

preferences:
362.5 ms | 402 KiB | 405 Q