How do I create 7-Zip archives with .NET?

EggCafe 7Zip cookie example This is an example (zipping cookie) with the DLL of 7Zip.

CodePlex Wrapper This is an open source project that warp zipping function of 7z.

7Zip SDK The official SDK for 7zip (C, C++, C#, Java) <---My suggestion

.Net zip library by SharpDevelop.net

CodeProject example with 7zip

SharpZipLib Many zipping

If you can guarantee the 7-zip app will be installed (and in the path) on all target machines, you can offload by calling the command line app 7z. Not the most elegant solution but it is the least work.

SevenZipSharp is another solution. Creates 7-zip archives...

Here's a complete working example using the SevenZip SDK in C#.

It will write, and read, standard 7zip files as created by the Windows 7zip application.

PS. The previous example was never going to decompress because it never wrote the required property information to the start of the file.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using SevenZip.Compression.LZMA;
using System.IO;
using SevenZip;

namespace VHD_Director
{
    class My7Zip
    {
        public static void CompressFileLZMA(string inFile, string outFile)
        {
            Int32 dictionary = 1 << 23;
            Int32 posStateBits = 2;
            Int32 litContextBits = 3; // for normal files
            // UInt32 litContextBits = 0; // for 32-bit data
            Int32 litPosBits = 0;
            // UInt32 litPosBits = 2; // for 32-bit data
            Int32 algorithm = 2;
            Int32 numFastBytes = 128;

            string mf = "bt4";
            bool eos = true;
            bool stdInMode = false;


            CoderPropID[] propIDs =  {
                CoderPropID.DictionarySize,
                CoderPropID.PosStateBits,
                CoderPropID.LitContextBits,
                CoderPropID.LitPosBits,
                CoderPropID.Algorithm,
                CoderPropID.NumFastBytes,
                CoderPropID.MatchFinder,
                CoderPropID.EndMarker
            };

            object[] properties = {
                (Int32)(dictionary),
                (Int32)(posStateBits),
                (Int32)(litContextBits),
                (Int32)(litPosBits),
                (Int32)(algorithm),
                (Int32)(numFastBytes),
                mf,
                eos
            };

            using (FileStream inStream = new FileStream(inFile, FileMode.Open))
            {
                using (FileStream outStream = new FileStream(outFile, FileMode.Create))
                {
                    SevenZip.Compression.LZMA.Encoder encoder = new SevenZip.Compression.LZMA.Encoder();
                    encoder.SetCoderProperties(propIDs, properties);
                    encoder.WriteCoderProperties(outStream);
                    Int64 fileSize;
                    if (eos || stdInMode)
                        fileSize = -1;
                    else
                        fileSize = inStream.Length;
                    for (int i = 0; i < 8; i++)
                        outStream.WriteByte((Byte)(fileSize >> (8 * i)));
                    encoder.Code(inStream, outStream, -1, -1, null);
                }
            }

        }

        public static void DecompressFileLZMA(string inFile, string outFile)
        {
            using (FileStream input = new FileStream(inFile, FileMode.Open))
            {
                using (FileStream output = new FileStream(outFile, FileMode.Create))
                {
                    SevenZip.Compression.LZMA.Decoder decoder = new SevenZip.Compression.LZMA.Decoder();

                    byte[] properties = new byte[5];
                    if (input.Read(properties, 0, 5) != 5)
                        throw (new Exception("input .lzma is too short"));
                    decoder.SetDecoderProperties(properties);

                    long outSize = 0;
                    for (int i = 0; i < 8; i++)
                    {
                        int v = input.ReadByte();
                        if (v < 0)
                            throw (new Exception("Can't Read 1"));
                        outSize |= ((long)(byte)v) << (8 * i);
                    }
                    long compressedSize = input.Length - input.Position;

                    decoder.Code(input, output, compressedSize, outSize, null);
                }
            }
        }

        public static void Test()
        {
            CompressFileLZMA("DiscUtils.pdb", "DiscUtils.pdb.7z");
            DecompressFileLZMA("DiscUtils.pdb.7z", "DiscUtils.pdb2");
        }
    }
}

I used the sdk.

eg:

using SevenZip.Compression.LZMA;
private static void CompressFileLZMA(string inFile, string outFile)
{
   SevenZip.Compression.LZMA.Encoder coder = new SevenZip.Compression.LZMA.Encoder();

   using (FileStream input = new FileStream(inFile, FileMode.Open))
   {
      using (FileStream output = new FileStream(outFile, FileMode.Create))
      {
          coder.Code(input, output, -1, -1, null);
          output.Flush();
      }
   }
}