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DeflateStream Constructor (Stream, CompressionLevel)

.NET Framework 4.5

Initializes a new instance of the DeflateStream class by using the specified stream and compression level.

Namespace:  System.IO.Compression
Assembly:  System (in System.dll)

public DeflateStream(
	Stream stream,
	CompressionLevel compressionLevel


Type: System.IO.Stream

The stream to compress.

Type: System.IO.Compression.CompressionLevel

One of the enumeration values that indicates whether to emphasize speed or compression efficiency when compressing the stream.


stream is null.


The stream does not support write operations such as compression. (The CanWrite property on the stream object is false.)

You use this constructor when you want to specify whether compression efficiency or speed is more important for an instance of the DeflateStream class.

This constructor overload uses the compression mode Compress. To set the compression mode to another value, use the DeflateStream(Stream, CompressionMode) or DeflateStream(Stream, CompressionMode, Boolean) overload.

The following example shows how to set the compression level when creating a DeflateStream object.

using System;
using System.Collections.Generic;
using System.IO;
using System.IO.Compression;

namespace ConsoleApplication
    class Program
        static void Main(string[] args)
            string directoryPath = @"c:\users\public\reports";
            DirectoryInfo directorySelected = new DirectoryInfo(directoryPath);

            foreach (FileInfo fileToCompress in directorySelected.EnumerateFiles())

        public static void Compress(FileInfo fileToCompress)
            using (FileStream originalFileStream = fileToCompress.OpenRead())
                if ((File.GetAttributes(fileToCompress.FullName) & FileAttributes.Hidden) != FileAttributes.Hidden & fileToCompress.Extension != ".cmp")
                    using (FileStream compressedFileStream = File.Create(fileToCompress.FullName + ".cmp"))
                        using (DeflateStream compressionStream = new DeflateStream(compressedFileStream, CompressionLevel.Fastest))

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1

Windows Phone 8.1, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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