Question

I need to create backup folders that increase in number. But I need to skip over gaps in numbering if they exist, and make the next folder name ONE higher than the highest numbered folder. For example if I have:

c:\backup\data.1
c:\backup\data.2
c:\backup\data.4
c:\backup\data.5

I need the next folder to be

c:\backup\data.6

The code below works but it feels awful clunky. Is there a better way to do this and still remain in .NET 2.0?

    static void Main(string[] args)
    {
        string backupPath = @"C:\Backup\";
        string[] folders = Directory.GetDirectories(backupPath);
        int count = folders.Length;
        List<int> endsWith = new List<int>();

        if (count == 0)
        {
            Directory.CreateDirectory(@"C:\Backup\Data.1");
        }
        else
        {
            foreach (var item in folders)
            {
                //int lastPartOfFolderName;
                int lastDotPosition = item.LastIndexOf('.');
                try
                {
                    int lastPartOfFolderName = Convert.ToInt16(item.Substring(lastDotPosition + 1));
                    endsWith.Add(lastPartOfFolderName);
                }
                catch (Exception)
                {
                   // Just ignore any non numeric folder endings
                }
            }
        }

        endsWith.Sort();

        int nextFolderNumber = endsWith[endsWith.Count - 1];
        nextFolderNumber++;

        Directory.CreateDirectory(@"C:\Backup\Data." + nextFolderNumber.ToString());
    }

Thanks

Answer 1

Here’s a slightly different version, but basically does the same thing. Find the folder with the max suffix and then add one to that for the next folder.

     static void Main(string[] args)
    {
        string backupPath = @"C:\Backup\";
        string[] folders = Directory.GetDirectories(backupPath);
        Int16 max = 0;

        foreach (var item in folders)
        {
            //int lastPartOfFolderName;
            int lastDotPosition = item.LastIndexOf('.');

            if (lastDotPosition > -1 && !item.EndsWith("."))
            {
                Int16 folderNumber;

                if (Int16.TryParse(item.Substring(lastDotPosition + 1), out folderNumber))
                {
                    if (folderNumber > max)
                    {
                        max = folderNumber;
                    }
                }
            }
        }

        max++;
        Directory.CreateDirectory(@"C:\Backup\Data." + max);
    }

I just ‘cleaned’ your code up a bit to remove the empty catch and the additional list / sort.