How to compress a Excel file to zip or cap file extention using C#

Question

I want to compress a Excel file to .zip or .cap extension. The code Used to do that it is compressing the file but that zip file can't be unzip. while unzip that i am getting the error file file corrupted or can't be unzip. The code I am using:

    static public bool CompressFile(string file, string outputFile)

      {

        try
        {

            using (var inFile = File.OpenRead(file))
            {

                using (var outFile = File.Create(outputFile))
                {

                    using (var compress = new GZipStream(outFile, CompressionMode.Compress, false))
                    {

                        byte[] buffer = new byte[inFile.Length];


                        int read = inFile.Read(buffer, 0, buffer.Length);

                        while (read > 0)
                        {
                            compress.Write(buffer, 0, read);
                            read = inFile.Read(buffer, 0, buffer.Length);
                        }
                    }
                }
            }
            return true;
        }
        catch (IOException ex)
        {
       MessageBox.Show(string.Format("Error compressing file: {0}", ex.Message));
            return false;
        }
    }

Even i go some link to get the proper solution. But nothing is workout.I need some suggestion to get the proper solution. Any answer please.

the code is working to compress to .zip. but i am not able to extract that zip file. while extracting it is showing no file to extract... — HomeWork, Jun 05 '14 at 09:06
You're using a `GZipStream`, which outputs GZip format (`.gz`), not ZIP format. — Frédéric Hamidi, Jun 05 '14 at 09:09
@FrédéricHamidi: I am new to it. let me try for .gz, but i want the sol for .zip — HomeWork, Jun 05 '14 at 09:10
@FrédéricHamidi: .gz all so not working for that code. if i am giving . .gz extension it is generating some "dll" kind of file which can't be extracted. any code u have to make .zip. — HomeWork, Jun 05 '14 at 09:15
Worth looking: http://msdn.microsoft.com/en-us/library/vstudio/system.io.compression.zipfile — Konstantin Smolyakov, Jun 05 '14 at 09:18
@KonstantinSmolyakov: I had through that link. it is using System.IO.Compression.FileSystem.dll. Where i will get that Dll. as i am using asp.net 3.5. in add reference that Dll is not present. — HomeWork, Jun 05 '14 at 09:25
@HomeWork Then it's easier to use some open source library like http://www.nuget.org/packages/DotNetZip/ — Konstantin Smolyakov, Jun 05 '14 at 09:27
@KonstantinSmolyakov: Thanks but i can't install anything without prior notice. can you suggest some other sol. — HomeWork, Jun 05 '14 at 09:32
@HomeWork Other solution: http://stackoverflow.com/questions/6386113/using-system-io-packaging-to-generate-a-zip-file — Konstantin Smolyakov, Jun 05 '14 at 09:38
@KonstantinSmolyakov: no that link all so not give me the sol. please anything suggest — HomeWork, Jun 05 '14 at 09:48
Have you tried the code in the exmaple for the [GZipStream class](http://msdn.microsoft.com/en-us/library/system.io.compression.gzipstream.aspx). Also for your info, xslx format is already compressed. — NoviceProgrammer, Jun 05 '14 at 09:49
@HomeWork Did you add reference to WindowsBase.dll to use System.IO.Packaging namespace? — Konstantin Smolyakov, Jun 05 '14 at 09:55
@HomeWork compressing an xlsx file is pointless because it's already Zip compressed. You'll probably increase the file's size instead of reducing it, as the `.zip` file will contain the original data with minimal compression, plus the headers required by the zip format — Panagiotis Kanavos, Jun 05 '14 at 10:46
@PanagiotisKanavos:ya but as my .xls file contains huge amount of data it is not able to attached in the mail. so it is needed to be compressed — HomeWork, Jun 05 '14 at 10:58
`xls` is a different format than `xslx`. `xls` is uncompressed, `xlsx` is zip-compressed — Panagiotis Kanavos, Jun 05 '14 at 11:29
@KonstantinSmolyakov:Hi as per your code i did the and it is compressing and working fin. but it is creating a blank XML file inside the zip folder with my .xls file. can you please help me out to remove that XML file. — HomeWork, Oct 09 '14 at 13:43

score 1 · Answer 1 · answered Jun 05 '14 at 10:37

This code uses the SharpZipLib library and will compress files that can be uncompressed no problems

    private void Zip()
    {
        string output = @"C:\TEMP\test.zip";
        string input = @"C:\TEMP\test.xlsx";

        using (var zipStream = new ZipOutputStream(System.IO.File.Create(output)))
        {
            zipStream.SetLevel(9);
            var buffer = new byte[4096];
            var entry = new ZipEntry(Path.GetFileName(input));
            zipStream.PutNextEntry(entry);

            using (FileStream fs = System.IO.File.OpenRead(input))
            {
                int sourceBytes;
                do
                {
                    sourceBytes = fs.Read(buffer, 0, buffer.Length);
                    zipStream.Write(buffer, 0, sourceBytes);
                } while (sourceBytes > 0);
            }

            zipStream.Finish();
            zipStream.Close();
        }
    }

Yes I can read comments, but firstly I answered the question that was asked. Secondly when I did this I did see a reduction in the size of file from 8.50kb to 5.25kb. So yes they maybe compressed, but that doesn't mean they can't be compressed more! — matt_lethargic, Jun 05 '14 at 10:49

How to compress a Excel file to zip or cap file extention using C#

1 Answers1