C#

public static void GZSerialize<T>(T instance, string baseFolderPath, string filename1)
{
    dcs = new DataContractSerializer(typeof(T));

    string fullfilename = baseFolderPath + "/" + filename1 + (usegzip + @".gz";

    //if (File.Exists(fullfilename ))
    //{
        //File.Delete(fullfilename );
    //}

    string fullfilename = @"C:\Users\Win-Ten\Desktop\fordata\test4.gz";

    // fails here
    using (FileStream compressedFileStream = new FileStream(fullfilename, FileMode.OpenOrCreate, FileAccess.Write))
    {
        using (GZipStream compressionStream =
               new GZipStream(compressedFileStream, CompressionLevel.Optimal, true))
        {
            dcs.WriteObject(compressionStream, instance);
            compressionStream.Close();
        }
    }
}

Queues: 
A queue is a "first in first out" data structure. Inserting elements is called 'enqueuing'. 
Removing/deleting elements from a queue is called 'dequeueing'. 
If you enqueue (insert) elements   in this order, then when you call dequeue, the 
first element removed is  . The second element would be   and so on. 
Input: 
Each input line will look like one of the following:
E  \n
D\n
where   is a number that will fit inside int  on the server.
Goal: 
Maintain a queue   of elements. Enqueue elements when input starts with "E". Dequeue when 
the input line is "D".
Output:
If the input line said "E  ", then enqueue (insert) the number   into  . No output!
If the input line said "D", then dequeue from   and print the number that was dequeued.
If a dequeue was requested on an empty queue, print "Empty".
Terminate all your output lines with \n .
Implementation Rules:
You must use a struct to maintain your queue. 
Use convenient typedef(s).
Create supporting functions.
Although in practice, you would create separate header file(s), we require you to put everything 
into just one .c file so that our evaluation server can be used.

public List<T> DatasettoList<T>(string commandText, CommandType commandType, IDbDataParameter[] parameters = null) where T : class, new()
        {
            DataSet dataSet = new DataSet();
            if ((commandType == null) || (commandText == null) || (commandText.Length == 0))
            {
                throw new Exception("Invailid command");
            }
            dataSet = GetDataSet(commandText, commandType, parameters);
            if (dataSet.Tables.Count == 0)
            {
                return null;
            }
            if (dataSet.Tables[0].Rows.Count == 0)
            {
                return null;
            }
            ProposalDownloadView prop = new ProposalDownloadView();
            List<ProposalDownloadView> proplist = new List<ProposalDownloadView>();
            List<T> list = new List<T>();
            var myData = dataSet.Tables[0].AsEnumerable().Select(r => new
            {
                UserId = r.Field<string>("UserId"),
                UseProposalNorId = r.Field<int>("UseProposalNorId"),
                FromDate = r.Field<decimal?>("FromDate"),
                ToDate = r.Field<decimal?>("ToDate")
            }).ToList();
            list = myData.ToList(); // this line creates the error
            return list;
        }