In PHP this function is used for case insensitive string comparisons using a "natural order" algorithm.

    strnatcasecmp(string1,string2)

In the above syntax "string1" is the first string to compare ,"string2" is the second string to compare.The function returns "0" if both strings are equal, returns a value "<0" if string1 is less than string2, returns a value ">0" if string1 is greater than string2.

    <?php
    echo strnatcasecmp("3Hi folks!","11Hi folks!");
    echo "<br/>";
    echo strnatcasecmp("11Hi folks!","3Hi folks!");
    ?>

    -1
    1

In the above example both string are same but the numbers are treated as strings and compared to display results.