How to get the all int values from a string which i pass like string str ="1,2,3-8,9" to an other string 1,2,3,4,5,6,7,8,9

//input string
string str ="1,3-8,9,10,12-21,30";

//get ranges (digit-digit)
//split them into Tuples(<int>,<int>) to be able to generate digits from-to
//finally - convert it into Enumerable<int>
var ranges = str.Split(new char[] {','}, StringSplitOptions.RemoveEmptyEntries)
			.Where(x=>x.Contains("-"))
			.Select(x=> Tuple.Create(Convert.ToInt32(x.Split(new char[]{'-'}, StringSplitOptions.RemoveEmptyEntries)[0]),
									Convert.ToInt32(x.Split(new char[]{'-'}, StringSplitOptions.RemoveEmptyEntries)[1])))
			.SelectMany(x=>Enumerable.Range(x.Item1, x.Item2-x.Item1+1));

//get digits 
//concat digit-ranges
//join digits into final string
var digits = string.Join(",", str.Split(new char[] {','}, StringSplitOptions.RemoveEmptyEntries)
				.Where(x=>!x.Contains("-"))
				.Select(x=>Convert.ToInt32(x))
				.Concat(ranges)
				.OrderBy(x=>x)
				.ToArray());
				
Console.WriteLine("final string: '{0}'", digits);

// 1. get all digits-digits|digits
//    note: any other characters are treated as separators
// 2. make for digits-digits: start number and number of items,
//     and for        digits: start number and number of items = 1
// 3. employ select-many to concatenate the ranges from 2 above
// 4. order by increasing numbers
var query = (from m in Regex.Matches(input, @"(\d+)(?:\s*-\s*(\d+))?").Cast<Match>()
                let a = int.Parse(m.Groups[1].Value)
                let v = m.Groups[2].Value
                let b = string.IsNullOrEmpty(v) ? a : int.Parse(v)
                let n = Math.Abs(b - a) + 1
                select new { a, n }
            )
            .SelectMany(t=>Enumerable.Range(t.a, t.n))
            .OrderBy(i=>i);

Console.WriteLine(string.Join(",", query));