- print_r: documentation ( source)
<?php
$a = [
0 => 'Sun',
1 => 'Mon',
2 => 'Tue',
3 => 'Wed',
4 => 'Thu',
5 => 'Fri',
6 => 'Sat'
];
$start = 0;
$r1 = $r2 = [];
foreach($a as $k => $v){
($k >= $start) ? ($r1[$k]=$v) : ($r2[$k]=$v);
}
$r = $r1 + $r2;
print_r($r);