Question

I have a string that might look something like this: “3, 7, 12-14, 1, 5-6”

What i need to do is to change that into a string looking like this: “1, 3, 5, 6, 7, 12, 13, 14”

I have made the following code work, but i would very much appreciated help how to do this a cleaner way with less lines of code:

private string sortLanes(string lanesString)
    {
        List<string> sortedLanes = new List<string>();

        if (lanesString.Contains(',') || lanesString.Contains('-'))
        {
            List<string> laneParts = lanesString.Split(',').ToList();

            foreach (string lanePart in laneParts)
            {
                if (lanePart.Contains('-'))
                {
                    int splitIndex = lanePart.IndexOf('-');
                    int lanePartLength = lanePart.Length;

                    int firstLane = Convert.ToInt32(lanePart.Substring(0, splitIndex));
                    int lastLane = Convert.ToInt32(lanePart.Substring(splitIndex + 1, lanePartLength - splitIndex - 1));
                    while (firstLane != lastLane)
                    {
                        sortedLanes.Add(firstLane.ToString().Trim());
                        firstLane++;
                    }
                    sortedLanes.Add(lastLane.ToString());
                }
                else
                {
                    sortedLanes.Add(lanePart.Trim());
                }
            }
            sortedLanes.Sort();
            sortedLanes = sortedLanes.OrderBy(x => x.Length).ToList();

            lanesString = "";
            foreach (string lane in sortedLanes)
            {
                if (lanesString.Length == 0)
                {
                    lanesString = lane;
                }
                else
                {
                    lanesString = lanesString + ", " + lane;
                }
            }
        }
        else
        {
            return lanesString;
        }
        return lanesString;
    }

Answer 1

I would first split by the , then convert each value into either a single integer or the desired range. Take the results and reorder them and then concatenate back into a string. Something like this.

    string test = "3, 7, 12-14, 1, 5-6";
    var items = test.Split(',');
    var ints = items.SelectMany(item => Expand(item));
    string result = string.Join(", ", ints.OrderBy(i => i).ToArray());


    private static IEnumerable<int> Expand(string str)
    {
        if (str.Contains('-'))
        {
            var range = str.Split('-');
            int begin = int.Parse(range[0]);
            int end = int.Parse(range[1]);
            for (int i = begin; i <= end; i++)
                yield return i;
        }
        else
            yield return int.Parse(str);
    }

Of course you might want to add some error checking, but I’ll leave that up to you.