left-shift.php

<?php

$arr = [1, 2, 3, 4, 5];

function rotLeft($a, $d) {
	$res = [];	
	$count = count($a);

	array_walk($a, function ($e, $i) use (&$a, $d, $count, &$res) {
		$res[$i] = $a[($i+$d)%$count];
	});

	return implode(' ', $res);
}