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# strnatcmp

(PHP 4 >= 4.0.0)

strnatcmp -- String comparisons using a "natural order" algorithm

## Description

``int strnatcmp` (string str1, string str2)`

This function implements a comparison algorithm that orders alphanumeric strings in the way a human being would, this is described as a "natural ordering". An example of the difference between this algorithm and the regular computer string sorting algorithms (used in strcmp()) can be seen below:

    $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);

The code above will generate the following output:

    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.

Similar to other string comparison functions, this one returns < 0 if `str1` is less than `str2`; > 0 if `str1` is greater than `str2`, and 0 if they are equal.

Note that this comparison is case sensitive.

See also ereg(), strcasecmp(), substr(), stristr(), strcmp(), strncmp(), strncasecmp(), strnatcasecmp(), strstr(), natsort() and natcasesort().

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