- join: documentation ( source)
<?php
function flatten(array $nestedArraysAndStrings){
$flat=[];
$iter = new RecursiveIteratorIterator(
new RecursiveArrayIterator($nestedArraysAndStrings));
foreach($iter as $leaf){ $flat[] = $leaf; }
return join(NULL, $flat);
}
$noRefs = [[[['some']]],[' nested ']," items n"];
$withRefs = []+$noRefs;
$wat = $noRefs[0];
$withRefs[0] = &$wat;
echo flatten($noRefs);
echo flatten($withRefs);