The natcasesort() function is an inbuilt function in PHP which is used to sort an array by using a "natural order" algorithm. The natural order tells the order to be used as a normal human being would use. That is, it does not check the type of value for comparison. For example, in string representation 30 is less than 7 according to the standard sorting algorithm as 3 comes before 7 lexicographically. But in natural order 30 is greater than 7. Also, the natcasesort() function is case insensitive. Syntax:

bool natcasesort($array )

Parameters: This function accepts a single parameter $array. It is the array which natcasesort() function is going to sort. Return Value It returns a boolean value i.e., TRUE on success and FALSE on failure. Below programs illustrate the natcasesort() function in PHP: Program 1: 

<?php

// input array
$arr1 = array("Gfg12.jpeg", "gfg10.jpeg", "Gfg2.jpeg", "gfg1.jpeg");
$arr2 = $arr1;

// sorting using sort function.
sort($arr1);
echo "Standard sorting\n";
print_r($arr1);

// Sorting using natcasesort() function.
natcasesort($arr2);
echo "Natural order case insensitive: ";
print_r($arr2);

?>

<?php

​

// input array

$arr1 = array("Gfg12.jpeg", "gfg10.jpeg", "Gfg2.jpeg", "gfg1.jpeg");

$arr2 = $arr1;

​

// sorting using sort function.

sort($arr1);

echo "Standard sorting\n";

print_r($arr1);

​

// Sorting using natcasesort() function.

natcasesort($arr2);

echo "Natural order case insensitive: ";

print_r($arr2);

​

?>

Output:

Standard sorting:
Array
(
    [0] => Gfg12.jpeg
    [2] => Gfg2.jpeg
    [3] => gfg1.jpeg
    [1] => gfg10.jpeg
)

Natural order case insensitive: 
Array
(
    [3] => gfg1.jpeg
    [2] => Gfg2.jpeg
    [1] => gfg10.jpeg
    [0] => Gfg12.jpeg
)

Program 2: 

<?php

// input array
$arr = array("Gfg15.jpeg", "gfg10.jpeg", "Gfg1.jpeg", 
                        "gfg22.jpeg", "Gfg2.jpeg");

// Sorting using natcasesort() function.
natcasesort($arr);

print_r($arr);

?>

<?php

​

// input array

$arr = array("Gfg15.jpeg", "gfg10.jpeg", "Gfg1.jpeg", 

                        "gfg22.jpeg", "Gfg2.jpeg");

​

// Sorting using natcasesort() function.

natcasesort($arr);

​

print_r($arr);

​

?>

Output:

Array
(
    [2] => Gfg1.jpeg
    [4] => Gfg2.jpeg
    [1] => gfg10.jpeg
    [0] => Gfg15.jpeg
    [3] => gfg22.jpeg
)

Reference: http://php.net/manual/en/function.natcasesort.php