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PHP usort() Function

PHP usort() Function

PHP usort() function is used to sort any given input array using the user-defined comparison function. It assigns a new integral key starting from zero to the number of elements present in the array and the old keys are lost. It returns a boolean type value TRUE in case of success and FALSE on failure.

Syntax:

 usort($array, function);

Parameter Values

Parameter Description
array This is a required parameter. It defines the array to sort.
function This is an optional parameter. It defines the callable comparison function.

Here is an example of usort() function in PHP:

<html>
<body>
<?php
function compare($a,$b)
{
if ($a==$b) return 0;
  return ($a<$b)?-1:1;
}
$arr=array(62,4,2,41,8,15,6,25);
usort($arr,"compare");
$length=count($arr);
for($x=0;$x<$length;$x++)
  {
  echo $arr[$x];
  echo "<br>";
  }
?> 
</body>
</html>
Output:
2
4
6
8
15
25
41
62

Example 2:

<html>
<body>
<pre>
<?php
function compare($a,$b)
{
if ($a==$b) return 0;
  return ($a<$b)?-1:1;
}
$arr=array(62,4,2,41,8,15,6,25);
usort($arr,"compare");
print_r($arr);
?> 
</pre>
</body>
</html>
Output:
Array
(
    [0] => 2
    [1] => 4
    [2] => 6
    [3] => 8
    [4] => 15
    [5] => 25
    [6] => 41
    [7] => 62
)

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