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PHP array_multisort() Function

PHP Array Reference Complete PHP Array Reference

Definition and Usage

The array_multisort() function returns a sorted array. You can assign one or more arrays. The function sorts the first array, and the other arrays follow, then, if two or more values are the same, it sorts the next array, and so on.

Syntax

array_multisort(array1,sorting order,sorting type,array2,array3...)

Parameter Description
array1 Required. Specifies an array
sorting order Optional. Specifies the sorting order. Possible values:
  • SORT_ASC Default. Sort in ascending order (A-Z)
  • SORT_DESC sort in descending order (Z-A)
sorting type Optional. Specifies the type to use, when comparing elements. Possible values:
  • SORT_REGULAR Default. Compare elements normally
  • SORT_NUMERIC Compare elements as numeric values
  • SORT_STRING Compare elements as string values
array2 Optional. Specifies an array
array3 Optional. Specifies an array

Tips and Notes

Tip: You can assign only one array to the array_multisort() function, or as many as you like.

Note: String keys will be maintained, but numeric keys will be re-indexed, starting at 0 and increase by 1.

Note: You can assign the sorting order and the sorting type parameters after each array. If you don't, each array parameter uses the default values.

Example 1

<?php
$a1=array("Dog","Cat");
$a2=array("Fido","Missy");
array_multisort($a1,$a2);
print_r($a1);
print_r($a2);
?>

The output of the code above will be:

Array ( [0] => Cat [1] => Dog )
Array ( [0] => Missy [1] => Fido )

Example 2

See how it sorts when two values are the same:

<?php
$a1=array("Dog","Dog","Cat");
$a2=array("Pluto","Fido","Missy");
array_multisort($a1,$a2);
print_r($a1);
print_r($a2);
?>

The output of the code above will be:

Array ( [0] => Cat [1] => Dog [2] => Dog ) 
Array ( [0] => Missy [1] => Fido [2] => Pluto )

Example 3

With sorting parameters:

<?php
$a1=array("Dog","Dog","Cat");
$a2=array("Pluto","Fido","Missy");
array_multisort($a1,SORT_ASC,$a2,SORT_DESC);
print_r($a1);
print_r($a2);
?>

The output of the code above will be:

Array ( [0] => Cat [1] => Dog [2] => Dog )
Array ( [0] => Missy [1] => Pluto [2] => Fido )

PHP Array Reference Complete PHP Array Reference

From http://www.w3schools.com (Copyright Refsnes Data)