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run code in 200+ php & hhvm versions
Bugs & Features
<?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)); $str = implode(array_reverse($arr)); echo $str;
based on 8JKFI