array_reverse
(PHP 4, PHP 5)
array_reverse — Return an array with elements in reverse order
Description
array array_reverse
( array
$array
[, bool $preserve_keys = false
] )
Takes an input array and returns a new array with
the order of the elements reversed.
Parameters
-
array -
The input array.
-
preserve_keys -
If set to
TRUEnumeric keys are preserved. Non-numeric keys are not affected by this setting and will always be preserved.
Return Values
Returns the reversed array.
Changelog
| Version | Description |
|---|---|
| 4.0.3 |
The preserve_keys parameter was added.
|
Examples
Example #1 array_reverse() example
<?php
$input = array("php", 4.0, array("green", "red"));
$reversed = array_reverse($input);
$preserved = array_reverse($input, true);
print_r($input);
print_r($reversed);
print_r($preserved);
?>
The above example will output:
Array
(
[0] => php
[1] => 4
[2] => Array
(
[0] => green
[1] => red
)
)
Array
(
[0] => Array
(
[0] => green
[1] => red
)
[1] => 4
[2] => php
)
Array
(
[2] => Array
(
[0] => green
[1] => red
)
[1] => 4
[0] => php
)
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Коментарии
This code can help in recursive reversing of the array...
<?php
$arr1 = array(2,1,array(5,2,1,array(9,8,7)),5,0);
$arr1 = array_reverse($arr1);
function Reverse_Array($array)
{ $index = 0;
foreach ($array as $subarray)
{ if (is_array($subarray))
{ $subarray = array_reverse($subarray);
$arr = Reverse_Array($subarray);
$array[$index] = $arr;
}
else {$array[$index] = $subarray;}
$index++;
}
return $array;
}
$arr2 = Reverse_Array($arr1);
?>
Needed to just reverse keys. Don't flog me if there is a better way. This was a simple solution.
<?php
function array_reverse_keys($ar){
return array_reverse(array_reverse($ar,true),false);
}
?>
Here are a couple of routines to swap the order of two elements in an array
<?php
function array_swap_forward($arr,$elem)
{
$ndx = array_search($elem,$arr) - 1;
$b4 = array_slice($arr,0,$ndx);
$mid = array_reverse(array_slice($arr,$ndx,2));
$after = array_slice($arr,$ndx + 2);
return array_merge($b4,$mid,$after);
}
function array_swap_back($arr,$elem)
{
$ndx = array_search($elem,$arr);
$b4 = array_slice($arr,0,$ndx);
$mid = array_reverse(array_slice($arr,$ndx,2));
$after = array_slice($arr,$ndx + 2);
return array_merge($b4,$mid,$after);
}
$arr =array('a','b','c','d','e','f');
print_r(array_swap_forward($arr,'c'));
echo '<br>';
print_r(array_swap_back($arr,'c'));
?>