DeflateStream Constructor (Stream, CompressionLevel)

.NET Framework (current version)

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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.

Exception Condition

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))

Universal Windows Platform
Available since 8
.NET Framework
Available since 4.5
Portable Class Library
Supported in: portable .NET platforms
Windows Phone
Available since 8.1
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