I need to recursively reverse a HUGE array that has many levels of sub arrays, and I need to preserve all of the keys (which some are int keys, and some are string keys), can someone please help me? Perhaps an example using array_reverse somehow? Also, is using array_reverse the only/best method of doing this?
Thanks :)
Try this:
function array_reverse_recursive($arr) {
foreach ($arr as $key => $val) {
if (is_array($val))
$arr[$key] = array_reverse_recursive($val);
}
return array_reverse($arr);
}
Recursively:
<?php
$a = array(1,3,5,7,9);
print_r($a);
function rev($a) {
if (count($a) == 1)
return $a;
return array_merge(rev(array_slice($a, 1, count($a) - 1)), array_slice($a, 0, 1));
}
$a = rev($a);
print_r($a);
?>
output:
Array
(
[0] => 1
[1] => 3
[2] => 5
[3] => 7
[4] => 9
)
Array
(
[0] => 9
[1] => 7
[2] => 5
[3] => 3
[4] => 1
)
Reversing a HUGE php array in situ (but not recursively):
function arrayReverse(&$arr){
if (!is_array($arr) || empty($arr)) {
return;
}
$rev = array();
while ( false !== ( $val = end($arr) ) ){
$rev[ key($arr) ] = $val;
unset( $arr[ key($arr) ] );
}
$arr = $rev;
}
//usage
$test = array(5, 'c'=>100, 10, 15, 20);
arrayReverse($test);
var_export($test);
// result: array ( 3 => 20, 2 => 15, 1 => 10, 'c' => 100, 0 => 5, )
