PHP uasort() function

The PHP uasort( ) function is used to sort an array by its values using a user-defined comparison function. This function was introduced in PHP 4.0.

Syntax

Parameter

Parameter	Description	Is compulsory
array	Specifies the array to be sorted.	compulsory
user_defined_function	This function is a comparison function and it is used to compare values and sort the array. This function returns three types of values. If a=b, return 0 If a>b, return 1 If a<b, return -1	Optional

Return type

The uasort( ) function returns true on success or false on failure.

Example 1

<?php
function   compare($a,$b)
{
if ($a==$b) return 0;
return ($a<$b)?-1:1;
}
$sports=array("a"=>"tennis","b"=>"badminton","c"=>"football","d"=>"cricket");
uasort($sports,"compare");
print_r($sports);
?>

Output:

Array
(
    [b] => badminton
    [d] => cricket
    [c] => football
    [a] => tennis
)

Example 2

<?php
function    usersort($x, $y)
{
if ($x == $y) return 0;
return ($x > $y) ? -1 : 1;
}
$car = array("1" => "datsun","2" => "tata", "5" => "audi","4" => "ford");
uasort($car, "usersort");
print_r ($car);
?>

Output:

Array
(
    [2] => tata
    [4] => ford
    [1] => datsun
    [5] => audi
)

Example 3

<?php
function   myfunction($a, $b) 
{
if ($a == $b) return 0;
return ($a > $b) ? -1 : 1;
}
$input = array("d"=>"coconut", "a"=>"apple", "b"=>"banana" );
   	uasort($input, "myfunction");
   	print_r($input);
?>

Output:

Array
(
    [d] => coconut
    [b] => banana
    [a] => apple
)

Example 4

<?php
function   sorting($x, $y) 
{
if ($x == $y) return 0;
return ($x > $y) ? -1 : 1;
}
$input = array("d"=>"1", "a"=>"2", "b"=>"3", "f"=>"4" );
uasort($input, "sorting");
print_r($input);
?>

Output:

Array
(
    [f] => 4
    [b] => 3
    [a] => 2
    [d] => 1
)

Next TopicPHP Array Functions

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