Ordering a List by string to find the newer version C#

Question

I have a folder with several Directories that are named after a version of an update such as UPDATE_20080311_3.5.9. I need to find the latest update on that list by veryfing the "3.5.9", I made a code to parse the name and add just the version to a list. Is there anyway to Sort tha list by using List.Sort in order to get the latest version "number"? This is the code I made so far, I don't know how to properly use the .Sort() method and if this can be done. I appreciate any help given

public string NewerVersion(string Directoria)
    {
        List<string> Lista = new List<string>();
        DirectoryInfo dir = new DirectoryInfo(Directoria);
        DirectoryInfo[] dirs = dir.GetDirectories();
        foreach (DirectoryInfo Info in dirs)
        {
            string Dir = Info.Name.ToString();
            Lista.Add(Dir.Substring(Dir.LastIndexOf('_'), Dir.Length));

        }
        Lista.Sort()
        //Lista.ToArray();
    }

Answer 1

You can use Version which implements IComparable, so it supports sorting.

For example with this LINQ query:

Version version = null;
Version lastVersion = new DirectoryInfo(Directoria).EnumerateDirectories()
    .Where(d => d.Name.StartsWith("UPDATE_"))
    .Select(d => new {Directory = d, Token = d.Name.Split('_')})
    .Where(x => x.Token.Length == 3 && Version.TryParse(x.Token[2], out version))
    .Select(x => new {x.Directory, Date = x.Token[1], Version = version})
    .OrderByDescending(x => x.Version)
    .Select(x => x.Version)
    .FirstOrDefault();
string latestVersion = lastVersion.ToString(); // if you want it as string

After I find the newer version I need to be able to return the name of the directory

Then use this query:

var lastVersion = new DirectoryInfo(Directoria).EnumerateDirectories()
    .Where(d => d.Name.StartsWith("UPDATE_"))
    .Select(d => new {Directory = d, Token = d.Name.Split('_')})
    .Where(x => x.Token.Length == 3 && Version.TryParse(x.Token[2], out version))
    .Select(x => new {x.Directory, Date = x.Token[1], Version = version})
    .OrderByDescending(x => x.Version)
    .FirstOrDefault();
if (lastVersion != null)
    Console.WriteLine(lastVersion.Directory.FullName);

Answer 2

When sorting by version, try using Version which is specially designed for that:

 List<String> Lista = new List<string>() {
    "UPDATE_20080311_3.5.9",
    "UPDATE_20080311_3.5.10",
    "UPDATE_20080311_3.4.11",
  };

  Lista.Sort((left, right) => {
    Version x = new Version(left.Substring(left.LastIndexOf('_') + 1));
    Version y = new Version(right.Substring(right.LastIndexOf('_') + 1));

    // or "return -x.CompareTo(y);" if you want to sort in descending order
    return x.CompareTo(y);
  });

  ...

  // UPDATE_20080311_3.4.11
  // UPDATE_20080311_3.5.9
  // UPDATE_20080311_3.5.10
  Console.Write(String.Join(Environment.NewLine, Lista);

Answer 3

Edit:

Continuing from your solution, there is a problem which the way you add your item:

string Dir = Info.Name.ToString();
Lista.Add(Dir.Substring(Dir.LastIndexOf('_'), Dir.Length));

Notice two mistakes here:

1. You get the Substring from LastIndexOf('_') instead of from LastIndexOf('_') + 1, which is what you really want
2. You use Dir.Length while you should use Dir.Length - LastIndexOf('_') + 1 instead

Change that into:

string Dir = Info.Name.ToString();
int indexStart = Dir.LastIndexOf('_') + 1;
Lista.Add(Dir.Substring(indexStart, Dir.Length - indexStart));

Then you could further process the Lista that you have populated to have the version number alone by LINQ OrderBy and ThenBy as well as string.Split('.')

var result = Lista.Select(x => x.Split('.'))
    .OrderBy(a => Convert.ToInt32(a[0]))
    .ThenBy(a => Convert.ToInt32(a[1]))
    .ThenBy(a => Convert.ToInt32(a[2]))
    .Last();
string finalVersion = string.Join(".", result);

To get the final version among the listed items.

To get your directory path back based on your finalVersion, simply do:

string myDirPath = dirs.Select(x => x.FullName).SingleOrDefault(f => f.EndsWith(finalVersion));

Answer 4

You can use Linq and Version

public string NewerVersion(string Directoria)
{
    return new DirectoryInfo(Directoria)
        .GetDirectories()
        .OrderByDescending(x => new Version(x.Name.Substring(x.Name.LastIndexOf('_') + 1)))
        .First()
        .Name;
}

If Directoria contains "UPDATE_20080311_3.5.9", "UPDATE_20090311_5.6.11", "UPDATE_20070311_1.5.9", will return "UPDATE_20090311_5.6.11"

Answer 5

I'm not sure about, whether this satisfies the requirement or not;if not please forgive me;

You are creating folders for each version release; so a version 3.5.7 will be created after 3.5.6 which is followed by 3.55 and the next version could be 3.58, So what i'am trying to say is that, they can be sorted on the basics of creation time. if so the following code will help you:

public static string NewerVersion(string Directoria)
{
    List<string> Lista = new List<string>();
    DirectoryInfo dir = new DirectoryInfo(Directoria);
    DirectoryInfo[] dirs = dir.GetDirectories();
    Lista = dirs.OrderBy(x => x.CreationTime).Select(y => y.Name.ToString()).ToList();
    //Lista will contains the required names
    //rest of code here
    return String.Join(Environment.NewLine, Lista);
}