3v4l.org

run code in 300+ PHP versions simultaneously
<?php $arr = array('a', 'b', 'c', 'd', 'e', 'f'); //$str = implode(array_walk(array_reverse($arr), function($v,$k){if($k%3==0)$v.=';';})); //print_r(array_map(function($v){if($k%3==0)$v.=';';}), array_reverse($arr)); $str = strrev(chunk_split(implode(array_reverse($arr)), 3, ';')); echo $str;
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, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.24 - 5.5.35, 5.6.7 - 5.6.28, 7.0.0 - 7.0.20, 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 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
;abc;def

preferences:
272.63 ms | 405 KiB | 341 Q