PHP, Structures and Functions of ARRAY

This function returns TRUE on success or FALSE on failure.

$array1_sort_flags can be swapped with $array1_sort_order or omitted entirely, in which case SORT_REGULAR is assumed.

Accepeted: $array2, $array3, ..., $arrayN optionally followed by sort order and flags.

Only elements corresponding to equivalent elements in previous arrays are compared.

In other words, the sort is lexicographical.


<?php

bool array_multisort ( arr &$array1 [, 
                         mix $array1_sort_order = SORT_ASC [, 
                         mix $array1_sort_flags = SORT_REGULAR [, 
                         mix $array2, ..., mix $arrayN ]]] )
 

where,

&$array1 = The input ARRAY to be sorted

$array1_sort_order = To control de sorting behavior
                                ( SEE the below TABLE )
                        
$array1_sort_flags = The sort options for the previous ARRAY
                                ( SEE the below TABLE )
                        
$array2 = The second ARRAY followed by sort order or flags

. . . . . . . . . . .

$arrayN = The last ARRAY followed by sort order or flags

?>

&$array

The input ARRAY. to be sorted

$array1_sort_order

It can be one of the following values:

CONSTANT	VALUE	OBSERVATIONS	DEFAULT
SORT_ASC	4	sort ascendingly	SORT_ASC
SORT_DESC	3	sort descendingly	SORT_ASC
ed48

$array1_sort_flags

It can be one of the following values:

CONSTANT	VALUE	OBSERVATIONS	DEFAULT
SORT_REGULAR	0	compare items normally (don't change types).	SORT_REGULAR
SORT_NUMERIC	1	compare items numerically
SORT_STRING	2	compare items as strings
SORT_LOCALE_STRING Does not work in PHP 8	5	compare items as strings, based on the current locale. It uses the locale, which can be changed using setlocale.
SORT_NATURAL	6	compare items as strings using "natural ordering" like natsort.
SORT_FLAG_CASE	8	can be combined (bitwise OR) with SORT_STRING or SORT_NATURAL to sort strings case-insensitively
ed48

EXERCISE


<?php

$arrms001 = [ 37, 17, 27, 7 ];

echo 'The given ARRAY:<br>';
print_r($arrms001);

array_multisort($arrms001);

echo '<br><br>ARRAY - DEFAULT:<br>';
print_r($arrms001);

?>

RESULT

The given ARRAY:
array
{
[0] => 37
[1] => 17
[2] => 27
[3] => 7
}

ARRAY - DEFAULT:
array
{
[0] => 7
[1] => 17
[2] => 27
[3] => 37
}

This is a one-dimensional ARRAY.

In the ordering there was a reordering of the keys.

EXERCISE


<?php

$arrms002a = [ "TEN" => "ten", 8 => "eight", "5" => "five" ];
$arrms002b = [ 0, 3, "SEVEN" ];

echo 'The given ARRAY (1):<br>';
print_r($arrms002a);


echo '<br><br>The given ARRAY (2):<br>';
print_r($arrms002b);
echo '<br><br><br>';

if(array_multisort($arrms002a, $arrms002b))
{
echo 'ARRAY (1) - SORT_REGULAR:<br>';
print_r($arrms002a);
echo '<br><br>ARRAY (2)  - SORT_REGULAR:<br>';
print_r($arrms002b);
}
else
{
echo 'It was not possible to sort any of the ARRAYS.';
}

?>

RESULT

The given ARRAY (1)
Array ( [TEN] => ten [8] => eight [5] => five )

The given ARRAY (2)
Array ( [0] => 0 [1] => 3 [2] => SEVEN )

ARRAY (1) - SORT_REGULAR:
Array ( [0] => eight [1] => five [TEN] => ten )

ARRAY (2) - SORT_REGULAR:
Array ( [0] => 3 [1] => SEVEN [2] => 0 )

EXERCISE


<?php

$arrms04a = [ "zero" => [ "ten" => 10, "eight" => 8 ], "five" => 5 ];

$arrms04b = [ "one" => [10 => "ten", 8 => "eight" ], 5 => "five" ];

echo 'ARRAY (1)<br>';
print_r($arrms04a);
echo '<br><br>';

echo 'ARRAY (2)<br>';
print_r($arrms04b);
echo '<br><br><br>';

array_multisort($arrms04a, 
            SORT_DESC, SORT_REGULAR, $arrms04b);

echo 'ARRAY (1) - SORT_DESC, SORT_REGULAR<br>';
print_r($arrms04a);

echo '<br><br>';
echo ' ARRAY (2) - SORT_DESC, SORT_REGULAR<br>';
print_r($arrms04b);

echo '<br><br><br>';

array_multisort($arrms04a, 
           SORT_ASC, SORT_REGULAR, $arrms04b);

echo 'ARRAY (1) - SORT_ASC, SORT_REGULAR<br>';
print_r($arrms04a);

echo '<br><br>';
echo 'ARRAY (2) - SORT_ASC, SORT_REGULAR<br>';
print_r($arrms04b);

?>

RESULT

ARRAY (1)
Array ( [zero] => Array ( [ten] => 10 [eight] => 8 ) [five] => 5 )

ARRAY (2)
Array ( [one] => Array ( [10] => ten [8] => eight ) [5] => five )

ARRAY (1) - SORT_DESC, SORT_REGULAR
Array ( [zero] => Array ( [ten] => 10 [eight] => 8 ) [five] => 5 )

ARRAY (2) - SORT_DESC, SORT_REGULAR
Array ( [one] => Array ( [10] => ten [8] => eight ) [0] => five )

ARRAY (2) - SORT_ASC, SORT_REGULAR
Array ( [five] => 5 [zero] => Array ( [ten] => 10 [eight] => 8 ) )

ARRAY (2) - SORT_ASC, SORT_REGULAR
Array ( [0] => five [one] => Array ( [10] => ten [8] => eight ) )

EXERCISE


<?php

$arrms05a = [ [ "ten" => 10, "eight" => 8 ], "five" => 5 ]; 

$arrms05b =  [ [10 => "ten", 8 => "eight" ], 5 => "five" ]; 

echo 'ARRAY (1)<br>';
print_r($arrms05a);
echo '<br><br>';

echo 'ARRAY (2)<br>';
print_r($arrms05b);
echo '<br><br><br>';

array_multisort($arrms05a, 
                SORT_ASC, SORT_REGULAR, $arrms05b);

echo 'ARRAY (1) - SORT_ASC, SORT_REGULAR<br>';
print_r($arrms05a);

echo '<br><br>';
echo 'ARRAY (2) - SORT_ASC, SORT_REGULAR<br>';
print_r($arrms05b);

echo '<br><br><br>';

array_multisort($arrms05a, 
                  SORT_DESC, SORT_REGULAR, $arrms05b);

echo 'ARRAY (1) - SORT_DESC, SORT_REGULAR<br>';
print_r($arrms05a);

echo '<br><br>';
echo 'ARRAY (2) - SORT_DESC, SORT_REGULAR<br>';
print_r($arrms05b);

?>

RESULT

ARRAY (1)
Array ( [0] => Array ( [ten] => 10 [eight] => 8 ) [five] => 5 )

ARRAY (2)
Array ( [0] => Array ( [10] => ten [8] => eight ) [5] => five )

ARRAY (1) - SORT_ASC, SORT_REGULAR
Array ( [five] => 5 [0] => Array ( [ten] => 10 [eight] => 8 ) )

ARRAY (2) - SORT_ASC, SORT_REGULAR
Array ( [0] => five [1] => Array ( [10] => ten [8] => eight ) )

ARRAY (1) - SORT_DESC, SORT_REGULAR
Array ( [0] => Array ( [ten] => 10 [eight] => 8 ) [five] => 5 )

ARRAY (2) - SORT_DESC, SORT_REGULAR
Array ( [0] => Array ( [10] => ten [8] => eight ) [1] => five )

EXERCISE


<?php

$arrms06a = [ 2, 4, -5, -3, 1 ]; 

$arrms06b =  [ 'two', 'four', 'minus five', 'minus three', 'one' ]; 

echo 'ARRAY (1)<br>';
print_r($arrms06a);
echo '<br><br>';

echo 'ARRAY (2)<br>';
print_r($arrms06b);
echo '<br><br><br>';

array_multisort($arrms06a, 
           SORT_ASC, SORT_STRING, $arrms06b);

echo 'ARRAY (1) - SORT_ASC, SORT_STRING<br>';
print_r($arrms06a);

echo '<br><br>';
echo 'ARRAY (2) - SORT_ASC, SORT_STRING<br>';
print_r($arrms06b);

array_multisort($arrms06a, 
            SORT_DESC, SORT_STRING, $arrms06b);

echo '<br><br>';
echo 'ARRAY (1) - SORT_DESC, SORT_STRING<br>';
print_r($arrms06a);

echo '<br><br>';
echo 'ARRAY (2) - SORT_DESC, SORT_STRING<br>';
print_r($arrms06b);

?>

RESULT

ARRAY (1)
Array ( [0] => 2 [1] => 4 [2] => -5 [3] => -3 [4] => 1 )

ARRAY (2)
Array ( [0] => two [1] => four [2] => minus five [3] => minus three [4] => one )

ARRAY (1) - SORT_ASC, SORT_STRING
Array ( [0] => -3 [1] => -5 [2] => 1 [3] => 2 [4] => 4 )

ARRAY (2) - SORT_ASC, SORT_STRING
Array ( [0] => minus three [1] => minus five [2] => one [3] => two [4] => four )

ARRAY (1) - SORT_DESC, SORT_STRING
Array ( [0] => 4 [1] => 2 [2] => 1 [3] => -5 [4] => -3 )

ARRAY (2) - SORT_DESC, SORT_STRING
rray ( [0] => four [1] => two [2] => one [3] => minus five [4] => minus three )

EXERCISE


<?php

echo "Basic functionality:<br><br>";

// Initialise all required variables
$ar1 = array("row1" => 2, "row2" => 1, "row3" => 1);
$ar2 = array("row1" => 2, "row2" => "aa", "row3" => "1");

echo "Testing with all normal arguments:<br>";
var_dump( array_multisort($ar1, SORT_ASC, SORT_REGULAR, 
                                           $ar2, SORT_DESC, SORT_STRING) );
echo '<br>';
var_dump($ar1, $ar2);

echo "<br><br>Testing with one argument:<br>";
var_dump( array_multisort($ar2) );
echo '<br>';
var_dump($ar2);

?>

EXERCISE


<?php

echo "Basic functionality - 
                        renumbering of numeric keys:<br><br>";

// Initialise all required variables
$ar1 = array( "strkey" => 2,  1,  9 => 1);
$ar2 = array( 2, "aa" , "1");

echo "Testing with all normal arguments:<br>";
var_dump( array_multisort($ar1, SORT_ASC, SORT_REGULAR, 
                                    $ar2, SORT_ASC, SORT_NUMERIC) );
echo '<br>';
var_dump($ar1, $ar2);

?>

EXERCISE


<?php

echo "Case-sensitive:<br><br>";

$a = array(
    'Second',
    'First.1',
    'First.2',
    'First.3',
    'Twentieth',
    'Tenth',
    'Third',
);

$b = array(
    '2 a',
    '1 bb 1',
    '1 bB 2',
    '1 BB 3',
    '20 c',
    '10 d',
    '3 e',
);

array_multisort($b, SORT_STRING, $a);
echo '<pre>';
var_dump($a, $b);
echo '</pre>';

?>

EXERCISE


<?php

echo "Case-insensitive:<br><br>";

$a = array(
    'Second',
    'First.1',
    'First.2',
    'First.3',
    'Twentieth',
    'Tenth',
    'Third',
);

$b = array(
    '2 a',
    '1 bb 1',
    '1 bB 2',
    '1 BB 3',
    '20 c',
    '10 d',
    '3 e',
);

array_multisort($b, SORT_STRING | SORT_FLAG_CASE, $a);

var_dump($a, $b);

?>

EXERCISE


<?php

echo "Testing natural sorting<br><br>";

$a = array(
    'Second',
    'First',
    'Twentieth',
    'Tenth',
    'Third',
);

$b = array(
    '2 a',
    '1 b',
    '20 c',
    '10 d',
    '3 e',
);

array_multisort($b, SORT_NATURAL, $a);

var_dump($a, $b);

?>

EXERCISE


<?php

echo "Testing natural sorting case-sensitive:<br><br>";

$a = array(
    'Second',
    'First.1',
    'First.2',
    'First.3',
    'Twentieth',
    'Tenth',
    'Third',
);

$b = array(
    '2 a',
    '1 bb 1',
    '1 bB 2',
    '1 BB 3',
    '20 c',
    '10 d',
    '3 e',
);

array_multisort($b, SORT_NATURAL, $a);

var_dump($a, $b);

?>

EXERCISE


<?php

// Something of a dummy example 
// where 0 and '0' are used as equal elements.

$ary1 = array_fill(0, 100, 0);
$origAry2 = $ary2 = array_merge(...array_fill(0, 50, [0, '0']));
array_multisort($ary1, $ary2);
var_dump($ary2 === $origAry2);

?>

EXERCISE


<?php

echo "Testing with anonymous arguments:<br><br>";

var_dump(array_multisort(array(1,3,2,4)));

?>

EXERCISE


<?php

echo "Testing with empty array:<br><br>";

var_dump(array_multisort(array()));

?>

EXERCISE


<?php

echo "Testing  with multiple array arguments:<br><br>";

$arr1 = array (4,3,3,3);
$arr2 = array (9,3,2,2);
$arr3 = array (9,9,2,1);

var_dump(array_multisort($arr1, $arr2, $arr3));

echo '<pre>';
var_dump($arr1);
echo '<br><br>';
var_dump($arr2);
echo '<br><br>';
var_dump($arr3);
echo '</pre>';

?>

EXERCISE


<?php

echo "Testing  all array sort specifiers:<br><br>";

$ar = array( 2, "aa" , "1");

array_multisort($ar, SORT_REGULAR, SORT_ASC);
var_dump($ar);
echo '<br><br>';

array_multisort($ar, SORT_STRING, SORT_ASC);
var_dump($ar);
echo '<br><br>';

array_multisort($ar, SORT_NUMERIC, SORT_ASC);
var_dump($ar);

?>

EXERCISE


<?php

echo "Testing  all array sort specifiers:<br><br>";

$ar = array( 2, "aa" , "1");

array_multisort($ar, SORT_REGULAR, SORT_DESC);
var_dump($ar);
echo '<br><br>'; 

array_multisort($ar, SORT_STRING, SORT_DESC);
var_dump($ar);
echo '<br><br>'; 

array_multisort($ar, SORT_NUMERIC, SORT_DESC);
var_dump($ar);

?>

EXERCISE


<?php

setlocale(LC_ALL, 'pt-PT', 'pt_PT');

$arn = [ 21.98, 3.8, 0.8, 1, 0 , 6 ];

array_multisort($arn, SORT_LOCALE_STRING);
echo '<pre>';
var_dump($arn);
echo '</pre>'; 

?>