Sort ranged numbers using PHP

function.sort_ranged_numbers.php

<?php

// Helper function

/**
 * Sorts ranged numbers
 * @param $a
 * @param $b
 * @return int
 */
function sort_ranged_numbers($a, $b)
{
    $a = trim($a);
    $b = trim($b);
    // pattern for ranged numbers like 3-5
    $rangedNumPatt = '/^(\d+)\s*-\s*(\d+)/';

    // example: 3, 4
    if (is_numeric($a) && is_numeric($b)) {
        if ($a == $b)
            return 0;
        return ($a < $b) ? -1 : 1;
    } // example: 1-3, 3-5
    else if (($r1 = preg_match($rangedNumPatt, $a, $m1)) && ($r2 = preg_match($rangedNumPatt, $b, $m2))) {
        // example: 1-3, 1-5
        if ($r1 && $r2) {
            // if first digits same, sort by 2nd digits
            if ($m1[0] == $m2[0]) {
                if ($m1[1] == $m2[1])
                    return 0;
                return ($m1[1] < $m2[1]) ? -1 : 1;
            } // sort by 1st digits
            else {
                if ($m1[0] == $m2[0])
                    return 0;
                return ($m1[0] < $m2[0]) ? -1 : 1;
            }
        }
    } // example: 1-3, 5
    else {
        // example: 1-3, 1
        if (($r1 = preg_match($rangedNumPatt, $a, $m1)) && $m1[0] == $b)
            return -1;
        // example: 1, 1-3
        else if (($r1 = preg_match($rangedNumPatt, $b, $m1)) && $m1[0] == $a)
            return 1;
        // example: 1-3, 5
        else {
            if ($a == $b)
                return 0;
            return ($a < $b) ? -1 : 1;
        }
    }
}

?>

sort-ranged-numbers.php

<?php

require('function.sort_ranged_numbers.php');

$numbers=array('1-2','3-4','1','1-3','3-8','2-4','2');
usort($numbers,'sort_ranged_numbers');

print_r($sizes);

/*
OUTPUT:

Array
(
    [0] => 1
    [1] => 1-2
    [2] => 1-3
    [3] => 2
    [4] => 2-4
    [5] => 3-4
    [6] => 3-8
)
*/
?>