array_reverse


php128 apg

RETURN an ARRAY with elements in reverse order.





If $preserve_keys = TRUE numeric keys are preserved.

Non-numeric keys are not affected by this setting and will always be preserved.



<?php

arr array_reverse ( arr $array [, bool $preserve_keys = FALSE ] )
 

where,

$array = The input ARRAY

$preserve_keys = To control if in the returned ARRAY
                               numeric keys will be preserved or not

?> 

$array


The input ARRAY.



$preserve_keys


To control if the ARRAY numeric keys will be preserved or not.

VALUES MEANING DEFAULT
FALSE The numeric keys will not be preserved FALSE
TRUE The numeric keys will be preserved
ed48


  1 EXERCISE   

<?php

echo 'THE GIVEN ARRAY:<br><br>';

$arr01 = [["R", "G", "B"], [255, 255, 255], "WHITE"];

var_dump($arr01);

echo '<br><br><br>AFTER array_reverse:<br><br>';

$rarr01 = array_reverse($arr01); 
// $preserve_keys = FALSE (DEFAULT)
// NUMERICAL INDICES WILL NOT BE PRESERVED

var_dump($rarr01);

?> 

 RESULT   

THE GIVEN ARRAY

array(3) { [0]=> array(3) { [0]=> string(1) "R" [1]=> string(1) "G" [2]=> string(1) "B" } [1]=> array(3) { [0]=> int(255) [1]=> int(255) [2]=> int(255) } [2]=> string(5) "WHITE" }

AFTER array_reverse

array(3) { [0]=> string(5) "WHITE" [1]=> array(3) { [0]=> int(255) [1]=> int(255) [2]=> int(255) } [2]=> array(3) { [0]=> string(1) "R" [1]=> string(1) "G" [2]=> string(1) "B" } }

  2 EXERCISE   

<?php

echo 'THE GIVEN ARRAY:<br><br>';

$arr02 = [["R", "G", "B"], [255, 255, 255], "WHITE"];

var_dump($arr02);

echo '<br><br><br>AFTER array_reverse:<br><br>';

$rarr02 = array_reverse($arr02, TRUE); 
// $preserve_keys = TRUE
// NUMERICAL INDICES WILL BE PRESERVED

var_dump($rarr02);

?> 

 RESULT   

THE GIVEN ARRAY

array(3) { [0]=> array(3) { [0]=> string(1) "R" [1]=> string(1) "G" [2]=> string(1) "B" } [1]=> array(3) { [0]=> int(255) [1]=> int(255) [2]=> int(255) } [2]=> string(5) "WHITE" }

AFTER array_reverse

array(3) { [2]=> string(5) "WHITE" [1]=> array(3) { [0]=> int(255) [1]=> int(255) [2]=> int(255) } [0]=> array(3) { [0]=> string(1) "R" [1]=> string(1) "G" [2]=> string(1) "B" } }

  3 EXERCISE   

<?php

echo 'THE GIVEN ARRAY:<br>'; 

$arr03 = array("R" => "RED", 
                        "G" => "GREEN", 
                        "B" => "BLUE", 
                        "8" => "eight");

print_r($arr03);

echo '<br><br><br>AFTER array_reverse:<br>';

$prsvndx03a = false; 
// The numeric keys will not be preserved

$rarr03a = array_reverse($arr03, $prsvndx03a);

print_r($rarr03a);

echo '<br><br><br>AFTER array_reverse:<br>';

$prsvndx03b = true; 
// The numeric keys will be preserved

$rarr03b = array_reverse($arr03, $prsvndx03b);

print_r($rarr03b);

?> 

 RESULT   

THE GIVEN ARRAY
Array ( [R] => RED [G] => GREEN [B] => BLUE [8] => eight )

AFTER array_reverse with $preserve_keys = FALSE
Array ( [0] => eight [B] => BLUE [G] => GREEN [R] => RED )

AFTER array_reverse with $preserve_keys = TRUE
Array ( [8] => eight [B] => BLUE [G] => GREEN [R] => RED )

  4 EXERCISE   

<?php

echo 'THE GIVEN ARRAY:<br>'; 

$arr04 = [ 'K' => 2, 'L' => 8, 'M' => 18, 
                'N' => 32, 'O' => 32, 'P' => 18, 'Q' => 8 ];   

print_r($arr04);

echo '<br><br><br>AFTER array_reverse:<br>';

$prsvndx04a = false; 
// The numeric keys will not be preserved

$rarr04a = array_reverse($arr04, $prsvndx04a);

print_r($rarr04a);

echo '<br><br><br>AFTER array_reverse:<br>';

$prsvndx04b = true; 
// The numeric keys will be preserved

$rarr04b = array_reverse($arr04, $prsvndx04b);

print_r($rarr04b);

?> 

  5 EXERCISE   

<?php

echo 'THE GIVEN ARRAY:<br>'; 

$arr05 = [ '1' => 'Brasil', 
                '2' => 'United States', 
                3 => 'Japan', 4 => 'Portugal'];   

print_r($arr05);

echo '<br><br><br>AFTER array_reverse:<br>';

$prsvndx05a = false; 
// The numeric keys will not be preserved

$rarr05a = array_reverse($arr05, $prsvndx05a);

print_r($rarr05a);

echo '<br><br><br>AFTER array_reverse:<br>';

$prsvndx05b = true; 
// The numeric keys will be preserved

$rarr05b = array_reverse($arr05, $prsvndx05b);

print_r($rarr05b);

?>