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<?php printf("2013-10-31, -1 month: %s\n" . "2013-10-31, first day of 1 month ago: %s\n" . "2013-10-31, first day 1 month ago: %s\n" . "2013-10-31, first day, -1 month: %s", date('m', strtotime('2013-10-31 -1 month')), date('m', strtotime('2013-10-31 first day of 1 month ago')), date('m', strtotime('2013-10-31 first day 1 month ago')), date('m', strtotime('2013-10-31 first day -1 month')));
Output for 5.3.3 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.10, 7.2.0 - 7.2.33, 7.3.12 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
2013-10-31, -1 month: 10 2013-10-31, first day of 1 month ago: 09 2013-10-31, first day 1 month ago: 09 2013-10-31, first day, -1 month: 10
Output for 5.3.0 - 5.3.2
2013-10-31, -1 month: 10 2013-10-31, first day of 1 month ago: 09 2013-10-31, first day 1 month ago: 09 2013-10-31, first day, -1 month: 09
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17
2013-10-31, -1 month: 10 2013-10-31, first day of 1 month ago: 01 2013-10-31, first day 1 month ago: 09 2013-10-31, first day, -1 month: 10

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