DotNetZip How to fix 0000000 CRC32 issue?

Question

I'm using DotNetZip to add multiple MemoryStreams to a single archive. So far, my code works when I select 1 or 2 files, but does not work if I add more. I found the difference is the CRC32 are all 00000000 for those bad archive. Is it something about the archive size? Any help is appreciated! My code in C#:

foreach(.....){
       var zipEntryName=.....//Get the file name in string;
       var UDocument = .....//Get a object
       var UStream = UDocument .GetStream();
       UStream.Seek(0, SeekOrigin.Begin);
       ZipEntry entry = zipFile.AddEntry(zipEntryName,UStream );
 }
 var outputStream = new MemoryStream();
            outputStream.Seek(0, SeekOrigin.Begin);
            zipFile.Save(outputStream);
            outputStream.Flush();
            return outputStream;

Answer 1

I think its beacuse of memory leakage. you are creating object in foreach loop and here the problem comes if the loop iterates more times.

here the problem comes in your code:

var UDocument = .....//Get a object

a singleton is a class that can be instantiated once, and only once. use singleton class as below:

public static SingletonSample InstanceCreation()
{
    private static object lockingObject = new object();
    if(singletonObject == null)
    {
         lock (lockingObject)
         {
             singletonObject = new SingletonSample();

         }
    }
    return singletonObject;
}