strnatcmp

String comparisons using a "natural order" algorithm

&reftitle.description; `int` `strnatcmp` `string` `string1` `string` `string2`

This function implements a comparison algorithm that orders alphanumeric strings in the way a human being would, this is described as a "natural ordering". Note that this comparison is case sensitive.

&reftitle.parameters;

`string1`

- The first string.

`string2`

- The second string.

&reftitle.returnvalues;

Similar to other string comparison functions, this one returns `-1` if `string1` is less than `string2`; `1` if `string1` is greater than `string2`, and `0` if they are equal.

&reftitle.changelog;

&Version; | &Description;
&standard.changelog.binary-safe-string-comparison;

&reftitle.examples;

An example of the difference between this algorithm and the regular computer string sorting algorithms (used in `strcmp`) can be seen below:

    <?php
    $arr1 = $arr2 = array("img12.png", "img10.png", "img2.png", "img1.png");
    echo "Standard string comparison\n";
    usort($arr1, "strcmp");
    print_r($arr1);
    echo "\nNatural order string comparison\n";
    usort($arr2, "strnatcmp");
    print_r($arr2);
    ?>

&example.outputs;

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

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

For more information see: Martin Pool's Natural Order String Comparison page.
&reftitle.seealso;

- `preg_match`
- `strcasecmp`
- `substr`
- `stristr`
- `strcmp`
- `strncmp`
- `strncasecmp`
- `strnatcasecmp`
- `strstr`
- `natsort`
- `natcasesort`