How to compress and decompress files in C# .NET 4.0 (GZip)

.NET 4.0 has a built-in gzip compress and decompress method.
.NET 4.5 has zip support.

This code shows how to use the .NET 4.0 gzip functionality. This also includes .NET 4.0 Client Profile
.NET 4.0 is supported by Windows XP and .NET 4.5 is NOT.

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public static void Decompress(FileInfo file) { using (FileStream inFile = file.OpenRead()) { //original file extension, ex. filename.exe.gz string orgName = file.FullName.Remove(file.FullName.Length - file.Extension.Length); //decompress file using (FileStream outFile = File.Create(orgName)) { using (GZipStream Decompress = new GZipStream(inFile, CompressionMode.Decompress)) { //write decompressed file byte[] buffer = new byte[4096]; int index; while ((index = Decompress.Read(buffer, 0, buffer.Length)) != 0) outFile.Write(buffer, 0, index); } } } } public static void Compress(FileInfo file) { using (FileStream inFile = file.OpenRead()) { //create target file using (FileStream outFile =File.Create(file.FullName + ".gz")) { using (GZipStream Compress = new GZipStream(outFile, CompressionMode.Compress)) { //write compressed file byte[] buffer = new byte[4096]; int index; while ((index = inFile.Read(buffer, 0, buffer.Length)) != 0) Compress.Write(buffer, 0, index); } } } }