3v4l.org

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<?php $list = '1,2,3,4'; preg_match_all('/^\d+|\G(?!^)(,?\d+)\K/', $list, $matches); print_r(array_map('array_filter', $matches));
Output for 7.1.0 - 7.1.33, 7.2.0 - 7.2.34, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.25, 8.4.1 - 8.4.12
Array ( [0] => Array ( [0] => 1 ) [1] => Array ( [1] => ,2 [2] => ,3 [3] => ,4 ) )
preferences:
111.17 ms | 408 KiB | 5 Q