PHP array_reverse() function

This function reverses the order of elements in an array.

Syntax

array_reverse(array, preserve_key);

The parameter 'array' specifies the name of the array. 'preserve_key' is an optional parameter. It specifies whether array preserve numeric key or not. It has boolean value 'true' OR 'false'. If it is set to true, then it preserves the numeric key.

Example

<?php
    $arr = array(10, 11, 35, 12, 44);
    $arr_revs = array_reverse($arr);
    print_r($arr_revs);
?>

Output :

Array ( [0] => 44 [1] => 12 [2] => 35 [3] => 11 [4] => 10 )

If you set the preserve_key to 'TRUE'

<?php
    $arr = array(10, 11, 35, 12, 44);
    $arr_revs = array_reverse($arr, true);
    print_r($arr_revs);
?>

Output :

Array ( [4] => 44 [3] => 12 [2] => 35 [1] => 11 [0] => 10 )

The preserve key parameter does not effect on non numeric key.

Example

<?php
    $arr = array(a=>10, b=>11, c=>35, f=>12, r=>44);
    $arr_revs = array_reverse($arr);
    Print_r($arr_revs);
    echo '<br/>';
    $arr_revs = array_reverse($arr, true);
    Print_r($arr_revs);
?>

Output :

Array ( [r] => 44 [f] => 12 [c] => 35 [b] => 11 [a] => 10 )
Array ( [r] => 44 [f] => 12 [c] => 35 [b] => 11 [a] => 10 )

Both results are same