Question

Here is the code

ZipFile zipnew = ZipFile.Read(strPath);
if (!File.Exists(path))
{
    using (ZipFile zip = new ZipFile())
    {
        zip.Save(path);
    }
}
    string tmpname = fpath + "\\abtemp";
    ZipFile zipold = ZipFile.Read(path);
    foreach (ZipEntry zenew in zipnew)
    {
        string flna = zenew.FileName.ToString();
        string tfn = '@' + flna.Replace("\\", "/");
        Stream fstream = File.Open(tmpname, FileMode.OpenOrCreate, FileAccess.Write);
        zenew.Extract(fstream);
        string l = fstream.Length.ToString();
        fstream.Close();

        using (StreamReader sr = new StreamReader(tmpname))
        {
            var zn = zipold.UpdateEntry(flna, sr.BaseStream);
            sr.Close();
            sr.Dispose();
            fstream.Dispose();
        }
    }

    zipnew.Dispose();
    File.Delete(tmpname);
    File.Delete(strPath);

The problem is: I get no error and there are no files merged into zipold from zipnew.
Zipold is a blank zip file

Answer 1

You’re code isn’t 100% clear to me, the variable tfn doesn’t seem to be used and i’m not quite following with all the disposes / deletes.
But on the bright side i did get your code working, the main problem was that you’re not calling the save method of zipold.

    string path = "d:\\zipold.zip";
    ZipFile zipnew = ZipFile.Read("d:\\zipnew.zip");
    if (!File.Exists(path))
    {
        using (ZipFile zip = new ZipFile())
        {
            zip.Save(path);
        }
    }
    string tmpname = "d:" + "\\temp.dat";
    ZipFile zipold = ZipFile.Read(path);
    foreach (ZipEntry zenew in zipnew)
    {
        string flna = zenew.FileName.ToString();
        //string tfn = '\\' + flna.Replace("\\", "/"); useless line
        Stream fstream = File.Open(tmpname, FileMode.OpenOrCreate, FileAccess.Write);
        zenew.Extract(fstream);
        string l = fstream.Length.ToString();
        fstream.Close();
        using (StreamReader sr = new StreamReader(tmpname))
        {
            var zn = zipold.UpdateEntry(flna, sr.BaseStream);
            zipold.Save();
            sr.Close();
            sr.Dispose();
            fstream.Dispose();
        }

    }
    zipnew.Dispose();