Working with ZIP Archives in C# (.NET): Complete Guide

Working with ZIP Archives in C# (.NET)

In modern .NET development, working with archives is one of the most common tasks. Whether it's packaging logs, creating backups, or transferring data over a network — the ability to efficiently compress and decompress files is essential for every C# developer. In this article, we will thoroughly examine two main approaches: the built-in System.IO.Compression namespace and the third-party library SharpZipLib.

Built-in .NET Tools: System.IO.Compression

Starting with .NET Framework 4.5, the platform provides a native API for working with ZIP archives. The main classes are located in the System.IO.Compression namespace.

Creating a ZIP Archive

To create an archive, use the ZipArchive class together with ZipFile:

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

string sourceDirectory = @"C:\\Data\\Reports";string zipPath = @"C:\\Archives\\reports.zip";

if (File.Exists(zipPath))    File.Delete(zipPath);

ZipFile.CreateFromDirectory(sourceDirectory, zipPath);Console.WriteLine("Archive created: " + zipPath);

Extracting an Archive

Extraction is done similarly using the ExtractToDirectory method:

string extractPath = @"C:\\Data\\Extracted";ZipFile.ExtractToDirectory(zipPath, extractPath);Console.WriteLine("Archive extracted to: " + extractPath);

Working with Individual Entries

For finer control, use ZipArchive directly:

using (FileStream zipStream = new FileStream(zipPath, FileMode.Open))using (ZipArchive archive = new ZipArchive(zipStream, ZipArchiveMode.Read)){    foreach (ZipArchiveEntry entry in archive.Entries)    {        Console.WriteLine($"File: {entry.FullName}, Size: {entry.Length} bytes");                // Extracting a specific file        entry.ExtractToFile(Path.Combine(extractPath, entry.FullName), true);    }}

SharpZipLib Library

SharpZipLib is a powerful third-party open-source library that provides advanced capabilities compared to built-in tools. It supports more formats (GZip, BZip2, Tar) and offers more flexible control over the compression process.

Installing SharpZipLib

Install the library via NuGet Package Manager:

Install-Package SharpZipLib

Or via .NET CLI:

dotnet add package SharpZipLib

Creating an Archive with SharpZipLib

using ICSharpCode.SharpZipLib.Zip;using ICSharpCode.SharpZipLib.Core;

string outputZip = @"C:\\Archives\\backup.zip";string[] filesToZip = Directory.GetFiles(@"C:\\Data\\Files", "*.*", SearchOption.AllDirectories);

using (FileStream fsOut = File.Create(outputZip))using (ZipOutputStream zipStream = new ZipOutputStream(fsOut)){    zipStream.SetLevel(9); // Maximum compression (0-9)

    foreach (string filename in filesToZip)    {        FileInfo fi = new FileInfo(filename);        string entryName = ZipEntry.CleanName(fi.Name);        ZipEntry newEntry = new ZipEntry(entryName);        newEntry.DateTime = fi.LastWriteTime;        newEntry.Size = fi.Length;

        zipStream.PutNextEntry(newEntry);

        byte[] buffer = new byte[4096];        using (FileStream fsInput = File.OpenRead(filename))        {            StreamUtils.Copy(fsInput, zipStream, buffer);        }        zipStream.CloseEntry();    }}

Extracting an Archive with SharpZipLib

string inputZip = @"C:\\Archives\\backup.zip";string outputDir = @"C:\\Data\\Restored";

using (FileStream fsIn = File.OpenRead(inputZip))using (ZipInputStream zipStream = new ZipInputStream(fsIn)){    ZipEntry entry;    while ((entry = zipStream.GetNextEntry()) !=