CompleteRange.php

<?php
/**
 * Class for complete the numbers from an input range
 * Restrictions: 
 *    - Letters are invalids, number only please.
 *    - If add negative numbers these are remove and
 *      the result init from a positive number like 1.
 *    - If add the zero number the result is empty string.
 * Execution using:
 * - From Code Inside, instance from Class:
 *       $cr = new CompleteRange​();
 *        echo $cr->build('5,8,19,34');
 */
class CompleteRange​
{
    var $output = array();
    function __construct()
    {
    }

    function positiveOnly($var)
    {
        // Return positive integer only
        return($var > 0);
    }

    /**
    * Complete Range
    */
    function build($inputString = null)
    {
        $input = explode(',', $inputString);
        $input = array_filter($input, "CompleteRange​::positiveOnly");
        if (count($input) > 0)
        {
            $range = range( isset($input[0]) ? $input[0]:1, array_pop($input));
            $result = array_diff($range, $input);
            $this->output = array_merge($input, $result);
            sort($this->output);
        }
        return "Input String:\n" . $inputString . "\n\n" . 
                "Result:\n" . implode(",", $this->output);
    }
}

$cr = new CompleteRange​();
echo $cr->build('-6,-4,5,8,');
?>