Sort an array using a "natural order" algorithm

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- Sort an array using a "natural order" algorithm

# natsort

(PHP 4, PHP 5, PHP 7, PHP 8)

natsort — Sort an array using a "natural order" algorithm

### Description

natsort(array `&$array`): true

This function implements a sort algorithm that orders alphanumeric strings in the way a human being would while maintaining key/value associations. This is described as a "natural ordering". An example of the difference between this algorithm and the regular computer string sorting algorithms (used in sort()) can be seen in the example below.

> Note:

> If two members compare as equal, they retain their original order. Prior to PHP 8.0.0, their relative order in the sorted array was undefined.

> Note:

> Resets array's internal pointer to the first element.

### Parameters

`array`

  The input array.

### Return Values

Always returns `true`.

### Changelog

Version | Description
--- | ---
8.2.0 | The return type is `true` now; previously, it was bool.

### Examples

Example #1 natsort() examples demonstrating basic usage

    <?php
    $array1 = $array2 = array("img12.png", "img10.png", "img2.png", "img1.png");

    asort($array1);
    echo "Standard sorting\n";
    print_r($array1);

    natsort($array2);
    echo "\nNatural order sorting\n";
    print_r($array2);
    ?>

The above example will output:

    Standard sorting
    Array
    (
        [3] => img1.png
        [1] => img10.png
        [0] => img12.png
        [2] => img2.png
    )

    Natural order sorting
    Array
    (
        [3] => img1.png
        [2] => img2.png
        [1] => img10.png
        [0] => img12.png
    )

For more information see: Martin Pool's » Natural Order String Comparison page.

Example #2 natsort() examples demonstrating potential gotchas

    <?php
    echo "Negative numbers\n";
    $negative = array('-5','3','-2','0','-1000','9','1');
    print_r($negative);
    natsort($negative);
    print_r($negative);

    echo "Zero padding\n";
    $zeros = array('09', '8', '10', '009', '011', '0');
    print_r($zeros);
    natsort($zeros);
    print_r($zeros);
    ?>

The above example will output:

    Negative numbers
    Array
    (
        [0] => -5
        [1] => 3
        [2] => -2
        [3] => 0
        [4] => -1000
        [5] => 9
        [6] => 1
    )
    Array
    (
        [2] => -2
        [0] => -5
        [4] => -1000
        [3] => 0
        [6] => 1
        [1] => 3
        [5] => 9
    )

    Zero padding
    Array
    (
        [0] => 09
        [1] => 8
        [2] => 10
        [3] => 009
        [4] => 011
        [5] => 0
    )
    Array
    (
        [5] => 0
        [1] => 8
        [3] => 009
        [0] => 09
        [2] => 10
        [4] => 011
    )

### See Also

- natcasesort() - Sort an array using a case insensitive "natural order" algorithm
- The comparison of array sorting functions
- strnatcmp() - String comparisons using a "natural order" algorithm
- strnatcasecmp() - Case insensitive string comparisons using a "natural order" algorithm