ziparchive

ziparchive.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.IO.Compression;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication5
{
  class Program
  {
    static void Main(string[] args)
    {

      var ms = new MemoryStream();
      
      var directory = new DirectoryInfo("files");
      FileInfo[] files = directory.GetFiles();
      var filestreams = new List<NamedStream>();

      foreach (var file in files)
      {
        using (var fs = file.OpenRead())
        {
          var ns = new NamedStream();
          fs.CopyTo(ns);
          ns.Name = file.Name;
          filestreams.Add(ns);
        }
      }

      using (var fs = File.OpenWrite("output.zip"))
      using (var zipped = ZipSomeFiles(filestreams))
      {
        zipped.CopyTo(fs);
      }

    }

    static MemoryStream ZipSomeFiles(IEnumerable<NamedStream> files)
    {
      var ms = new MemoryStream();

      using (var zip = new ZipArchive(ms, ZipArchiveMode.Update, true))
      {
        foreach (NamedStream file in files)
        {
          var zipentry = zip.CreateEntry(file.Name, CompressionLevel.Optimal);
          using (var entry = zipentry.Open())
          {
            file.Position = 0;
            file.CopyTo(entry);
            file.Flush();//not needed in this example
          }
        }
      }
      ms.Position = 0;
      return ms;
    }
  }

  public class NamedStream : MemoryStream
  {
    public string Name { get; set; }

  }
}