- array_keys: documentation ( source)
<?php
$array = array ('a','b','c','d');
$keys = array_keys($array);
for ($i = 0; $i < count($keys); $i++) {
$cur = $array[$keys[$i]];
$next = $array[$keys[$i+1]];
echo "current item: ".$cur;
echo "\n";
echo "current item: ".$next;
}