PHP Tutorial - PHP ksort() Function

Definition

The ksort() function takes an array and sorts it by its keys while preserving the values.

Syntax

PHP ksort() Function has the following syntax.

bool ksort ( array &arr [, int options] )

Parameter

Parameter	Is Required	Description
array	Required.	Specifies the array to sort
sortingtype	Optional.	Specifies how to compare the array elements/items.

Possible values for sortingtype:

Value	Description
0 = SORT_REGULAR	Default. Compare items normally without changing types
1 = SORT_NUMERIC	Compare items numerically
2 = SORT_STRING	Compare items as strings
3 = SORT_LOCALE_STRING	Compare items as strings, based on current locale
4 = SORT_NATURAL	Compare items as strings using natural ordering
5 = SORT_FLAG_CASE	an be combined (bitwise OR) with SORT_STRING or SORT_NATURAL to sort strings case-insensitively

Note

Use the krsort() function to sort an associative array in descending order, according to the key.

Use the asort() function to sort an associative array in ascending order, according to the value.


<?PHP
    $capitalcities['A'] = 'Z';
    $capitalcities['B'] = 'X';
    $capitalcities['C'] = 'Y';
    ksort($capitalcities);
    print_r($capitalcities);
?>

ksort() works by reference, directly changing the array. The return value is either true or false, depending on whether the sorting was successful.

The code above generates the following result.

Example 1

We can pass a second parameter to the sort functions to specify how you want the values sorted, like this:


<?PHP//w  w  w. j a  v  a2 s .  com
    $array["1"] = "1";
    $array["2"] = "2";
    $array["3"] = "3";
    $array["10"] = "10";
    $array["100"] = "100";
    var_dump($array);
    ksort($array, SORT_STRING);
    var_dump($array);
?>

If you want to force a strictly numeric sort, you can pass SORT_NUMERIC as the second parameter.

The code above generates the following result.

Example 2

Sort an associative array in ascending order, according to the key:


<?php
$age=array("PHP"=>"5","Java"=>"7","java2s.com"=>"3");
ksort($age);
?>