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<?php $tag = "MU"; $string = 'D109 MU, worked from home today Walked the dog, later took the kids to swimming. D110 MU. Went to the gym in the evening for the 9th time this month.'; var_export(preg_match_all("~D\K\d+(?= $tag)~", $string, $out) ? $out[0] : 'fail');
Output for 5.6.38, 7.1.0 - 7.1.25, 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 - 8.1.30, 8.2.0 - 8.2.25, 8.3.0 - 8.3.13
array ( 0 => '109', 1 => '110', )
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67.73 ms | 407 KiB | 5 Q