PHP Tutorial - PHP array_multisort() Function

Definition

array_multisort() sorts multiple related arrays at the same time, preserving the relationship between the arrays.

String keys will be maintained, but numeric keys will be re-indexed.

Syntax

PHP array_multisort() Function has the following syntax.

array_multisort(array1,sortOrder,sortType,array2,array3...)

Parameter

Parameter	Is Required	Description
array1	Required.	Array to sort
sortOrder	Optional.	Sort Order.
sortType	Optional.	Type to use to compare elements.
array2	Optional.	Array to sort
array3	Optional.	Array to sort

Possible values for sortOrder:

Value	Description
SORT_ASC	Default. Sort in ascending order (A-Z)
SORT_DESC	Sort in descending order (Z-A)

Possible values for sortType:

Value	Description
SORT_REGULAR	Default. Compare elements as ASCII value
SORT_NUMERIC	Compare elements as numeric values
SORT_STRING	Compare elements as string values
SORT_LOCALE_STRING	Compare elements as string, based on the current locale which can be changed using setlocale()
SORT_NATURAL	Compare elements as strings using "natural ordering" like natsort()
SORT_FLAG_CASE	Can be combined (bitwise OR) with SORT_STRING or SORT_NATURAL to sort strings case-insensitively

Example 1

Using sorting parameters:


<?php
    $a1=array("P","J","H");
    $a2=array("PHP","Java","HTML");
    array_multisort($a1,SORT_ASC,$a2,SORT_DESC);
    print_r($a1);
    print_r($a2);
?>

The code above generates the following result.

Example 2

Merge two arrays and sort them as numbers, in descending order:


<?php
    $a1=array(1,3,5,7,9);
    $a2=array(4,3,2,1,6);
    $num=array_merge($a1,$a2);
    array_multisort($num,SORT_DESC,SORT_NUMERIC);
    print_r($num);
?>

The code above generates the following result.

Example 3

The following script stores book information in three related arrays. By passing all three arrays to array_multisort(), the arrays are all sorted according to the values in the first array:


<?PHP/* www.  j  ava 2 s . c  om*/
$authors = array( "Java", "PHP", "CSS", "HTML" ); 
$titles = array( "Learn Java from java2s.com", "Learn PHP from java2s.com", "Learn CSS from java2s.com", "Learn HTML from java2s.com" ); 
$pubYears = array( 2000, 2001, 2002, 2003 ); 

array_multisort( $authors, $titles, $pubYears ); 
print_r ( $authors ); 
print "\n";
print_r ( $titles ); 
print "\n";
print_r ( $pubYears );   
print "\n";
array_multisort( $titles, $authors, $pubYears );  
print_r ( $authors ); 
print "\n";
print_r ( $titles ); 
print "\n";
print_r ( $pubYears );   
print "\n";
?>

The code above generates the following result.

Example 4

Use array_multisort() to sort multidimensional arrays.

The function then sorts the array by the first element of each nested array, then by the second element of each nested array, and so on.

The order of the elements in the nested array is untouched.


<?php //from  ww w .  j a v a2 s  .  c om
     $myBooks = array( 
      array( 
        "title" =>  "Learn PHP from java2s.com", 
        "author" =>  "java2s.com", 
        "pubYear" =>  2000 
      ), 
      array( 
        "title" =>  "Oracle", 
        "author" =>  "java2s.com", 
        "pubYear" =>  1962 
      ), 
      array( 
        "title" =>  "Learn Java from java2s.com", 
        "author" =>  "JavaAuthor", 
        "pubYear" =>  2001 
      ), 
      array( 
        "title" =>  "Learn HTML from java2s.com", 
        "author" =>  "HTMLAuthor", 
        "pubYear" =>  2002 
      ), 
      array( 
        "title" =>  "Learn CSS from java2s.com", 
        "author" =>  "CSSAuthor", 
        "pubYear" =>  2003 
      ), 
     ); 
     array_multisort( $myBooks ); 
     print_r( $myBooks );
?>

The code above generates the following result.