Parse a string, and convert it into a series of sequential numbers.

gistfile1.php

<?php

/**
 * Parse a string, and convert it into a series of sequential numbers.
 * It works similar to Acrobat's print specified pages input box.
 * 
 * Examples:
 * 
 *     input: "1, 2, 3, 4, 5, 6" --> output: 1, 2, 3, 4, 5, 6
 *     input: "1-6" 			 --> output: 1, 2, 3, 4, 5, 6
 *     input: "1-6" 			 --> output: 1, 2, 3, 4, 5, 6
 *     input: "1 - -6" 			 --> output: 1, 2, 3, 4, 5, 6
 *     input: "0 - 0" 			 --> output: 0
 *     input: "1, 4-6, 2" 		 --> output: 1, 2, 4, 5, 6
 *     input: "6,3-1" 			 --> output: 1, 2, 3, 6
 *
 *  // Sample Usage:
 * $range = range_string("6, 3-1");
 * 
 * @author Jay Williams <myd3.com>
 * @license MIT License
 * @link http://gist.github.com/125557
 */

define('RANGE_ARRAY_SORT', 1);
define('RANGE_ARRAY', 2);
define('RANGE_STRING_SORT', 3);
define('RANGE_STRING', 4);

function range_string($range_str, $output_type = RANGE_ARRAY_SORT)
{
	// Remove spaces and nother non-essential characters
	$find[]    = "/[^\d,\-]/";
	$replace[] = "";
	
	// Remove duplicate hyphens
	$find[]    = "/\-+/";
	$replace[] = "-";
	
	// Remove duplicate commas
	$find[]    = "/\,+/";
	$replace[] = ",";
	
	$range_str = preg_replace($find, $replace, $range_str);

	// Remove any commas or hypens from the end of the string
	$range_str = trim($range_str,",-");
	
	$range_out = array();
	$ranges    = explode(",", $range_str);
	
	foreach($ranges as $range)
	{
		
		if(is_numeric($range) || strlen($range) == 1)
		{
			// Just a number; add it to the list.
			$range_out[] = (int) $range;
		}
		else if(is_string($range))
		{
			
			// Is probably a range of values.
		   $range_exp = preg_split("/(\D)/",$range,-1,PREG_SPLIT_DELIM_CAPTURE);
		
			$start = $range_exp[0];
			$end   = $range_exp[2];
		
			if($start > $end)
			{
				for($i = $start; $i >= $end; $i -= 1)
				{
					$range_out[] = (int) $i;
				}
			}
			else
			{
				for($i = $start; $i <= $end; $i += 1)
				{
					$range_out[] = (int) $i;
				}
			}
			
		}
	}
	
	switch ($output_type) {
		case RANGE_ARRAY_SORT:
			$range_out = array_unique($range_out);
			sort($range_out);
			
		case RANGE_ARRAY:
			return $range_out;
			break;
			
		case RANGE_STRING_SORT:
			$range_out = array_unique($range_out);
			sort($range_out);
			
		case RANGE_STRING:
		
		default:
			return implode(", ", $range_out);
			break;
	}
}


?>