php array_multisort Detailed explanation and example code for sorting arrays

The array_multisort() function in php can be used to sort multiple arrays at one time, or to sort multi-dimensional arrays according to a certain dimension or multiple dimensions. This article explains to you how to use the array_multisort function.

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

Note: String key names will be preserved, but numeric key names will be re-indexed, starting at 0 and increasing by 1.

Note: You can set the sort order and sort type parameters after each array. If not set, each array parameter will use its default value.

Syntax

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

Parameter description

Return value

Returns TRUE on success, or FALSE on failure.

Description

array_multisort() function sorts multiple arrays or multidimensional arrays.

The array in the parameter is treated as a table column and sorted by row - this is similar to the function of SQL's ORDER BY clause. The first array is the main array to be sorted. If the rows (values) in the array compare to be the same, they will be sorted according to the size of the corresponding value in the next input array, and so on.

The first parameter is an array, and each subsequent parameter may be an array or one of the following sort order flags (the sort flag is used to change the default sort order):

SORT_ASC - Default, sort in ascending order. (A-Z)
SORT_DESC - Sort in descending order. (Z-A)

You can then specify the type of sort:

SORT_REGULAR - Default. Arrange each item in regular order.
SORT_NUMERIC - Sort each item in numerical order.
SORT_STRING - Sort each item in alphabetical order.

Example 1:

Sort multi-dimensional array

<?php
 $ar = array(
    array("10",11,100,100,"a"),
    array(1,2,"2",3,1)
   );
 array_multisort($ar[0], SORT_ASC,SORT_STRING,$ar[1],SORT_NUMERIC,SORT_DESC);
 var_dump($ar);
?>

In this example, after sorting, the first array will become "10", 100, 100, 11, "a" (treated as a string in ascending order). The second array will contain 1, 3, "2", 2, 1 (treated as numbers in descending order).

Run result:

array(2) {
 [0]=> array(5) {
  [0]=> string(2) "10"
  [1]=> int(100)
  [2]=> int(100)
  [3]=> int(11)
  [4]=> string(1) "a"
 }
 [1]=> array(5) {
  [0]=> int(1)
  [1]=> int(3)
  [2]=> string(1) "2"
  [3]=> int(2)
  [4]=> int(1)
 }
}

Example 2:

Case-insensitive sorting

SORT_STRING and SORT_REGULAR are case-sensitive, and uppercase letters will be sorted before lowercase letters.
To perform case-insensitive sorting, you must sort based on the lowercase letter copy of the original array.

<?php
 $array=array(&#39;Alpha&#39;,&#39;atomic&#39;,&#39;Beta&#39;,&#39;bank&#39;);
 $array_lowercase=array_map(&#39;strtolower&#39;,$array);
 array_multisort($array_lowercase,SORT_ASC,SORT_STRING,$array);
 print_r($array);
?>

Run result:

Array
(
  [0] => Alpha
  [1] => atomic
  [2] => bank
  [3] => Beta
)

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