How to compress files in C#

Many members have asked me how to compress files in C#. Here is some cool code I found on MSDN that uses GZipStream class available in .NET Framework 3.0 and later versions to compress files in C#. I plan to write a file compression utility soon that will be based on this class.



using System;
using System.IO;
using System.IO.Compression;

public class GZipTest
{
 public static int ReadAllBytesFromStream(Stream stream, byte[] buffer) 
    {
 // Use this method is used to read all bytes from a stream.
 int offset = 0;
 int totalCount = 0;
 while (true) 
        {
 int bytesRead = stream.Read(buffer, offset, 100); 
 if ( bytesRead == 0) 
            {
 break; 
            }
    offset += bytesRead;
    totalCount += bytesRead; 
        }
 return totalCount;
    } 

 public static bool CompareData(byte[] buf1, int len1, byte[] buf2, int len2) 
    {
 // Use this method to compare data from two different buffers.
 if (len1 != len2) 
        { 
        Console.WriteLine("Number of bytes in two buffer are different {0}:{1}", len1, len2);
 return false;
        }

 for ( int i= 0; i< len1; i++) 
        {
 if ( buf1[i] != buf2[i]) 
            {
            Console.WriteLine("byte {0} is different {1}|{2}", i, buf1[i], buf2[i]);
 return false;
            }
        }
    Console.WriteLine("All bytes compare.");
 return true; 
    }

 public static void GZipCompressDecompress(string filename)
    {
    Console.WriteLine("Test compression and decompression on file {0}", filename);
    FileStream infile;
 try
        {
 // Open the file as a FileStream object.
        infile = new FileStream(filename, FileMode.Open, FileAccess.Read, FileShare.Read);
        byte[] buffer = new byte[infile.Length];
 // Read the file to ensure it is readable.
 int count = infile.Read(buffer, 0, buffer.Length);
 if ( count != buffer.Length) 
            {
            infile.Close();
            Console.WriteLine("Test Failed: Unable to read data from file"); 
 return;
            }
        infile.Close();
        MemoryStream ms = new MemoryStream();
 // Use the newly created memory stream for the compressed data.
        GZipStream compressedzipStream = new GZipStream(ms , CompressionMode.Compress, true);
        Console.WriteLine("Compression");
        compressedzipStream.Write(buffer, 0, buffer.Length);
 // Close the stream.
        compressedzipStream.Close();
        Console.WriteLine("Original size: {0}, Compressed size: {1}", buffer.Length, ms.Length);

 // Reset the memory stream position to begin decompression.
        ms.Position = 0;
        GZipStream zipStream = new GZipStream(ms, CompressionMode.Decompress);
        Console.WriteLine("Decompression");
        byte[] decompressedBuffer = new byte[buffer.Length + 100];
 // Use the ReadAllBytesFromStream to read the stream.
 int totalCount = GZipTest.ReadAllBytesFromStream(zipStream, decompressedBuffer);
        Console.WriteLine("Decompressed {0} bytes", totalCount);

 if( !GZipTest.CompareData(buffer, buffer.Length, decompressedBuffer, totalCount) ) 
        {
        Console.WriteLine("Error. The two buffers did not compare.");
        }
    zipStream.Close(); 
        } // end try
 catch (InvalidDataException)
        {
            Console.WriteLine("Error: The file being read contains invalid data.");
        }
 catch (FileNotFoundException)
        {
            Console.WriteLine("Error:The file specified was not found.");
        }
 catch (ArgumentException)
        {
            Console.WriteLine("Error: path is a zero-length string, contains only white space, or contains one or more invalid characters");
        }
 catch (PathTooLongException)
        {
            Console.WriteLine("Error: The specified path, file name, or both exceed the system-defined maximum length. For example, on Windows-based platforms, paths must be less than 248 characters, and file names must be less than 260 characters.");
        }
 catch (DirectoryNotFoundException)
        {
            Console.WriteLine("Error: The specified path is invalid, such as being on an unmapped drive.");
        }
 catch (IOException)
        {
            Console.WriteLine("Error: An I/O error occurred while opening the file.");
        }
 catch (UnauthorizedAccessException)
        {
            Console.WriteLine("Error: path specified a file that is read-only, the path is a directory, or caller does not have the required permissions.");
        }
 catch (IndexOutOfRangeException)
        {
            Console.WriteLine("Error: You must provide parameters for MyGZIP.");
        }
    }
 public static void Main(string[] args)
    {
 string usageText = "Usage: MYGZIP <inputfilename>";
 //If no file name is specified, write usage text.
 if (args.Length == 0)
        {
            Console.WriteLine(usageText);
        }
 else
        {
 if (File.Exists(args[0]))
                GZipCompressDecompress(args[0]);
        }
    }
}