Strange behaviour Generic List

Question

I have written some code to delete minor versions after a specific time. I don't know how it is possible, but it only deletes uneven versions, and not the even ones.

Below part is to find all versions that belongs to a specific major version.

   minorVersionList = versions.FindAll(x => x.VersionLabel.StartsWith(startLabel) && !x.VersionLabel.EndsWith(".0"));



                            SPFileVersionCollection versionCollection = item.File.Versions;
                            List<SPFileVersion> sortedList = minorVersionList.OrderBy(x => x.ID).ToList();
                            for (int i = 0; i <= sortedList.Count - 3; i++)
                            {

                                Console.WriteLine("Deleting Minor Version");
                                try
                                {
                                    versionCollection.DeleteByID(sorted[i].ID);
                                }
                                catch (Exception ex)
                                {
                                    Console.WriteLine(ex.InnerException);
                                }
                            }

Say I have the following SPFileVersions:

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

It deletes always the uneven numbers. The SortedList Generic List is being updated every time a Minor version is deleted.

Can someone help with this?

Answer 1

After some communication with an old colleague, I found out that when one of the collections is being updated, the other gets updated to... It is default behaviour of System.Collections like ReadOnlyCollection<>.