StreamWriter Constructor (Stream, Encoding, Int32, Boolean)

StreamWriter Constructor (Stream, Encoding, Int32, Boolean)

.NET Framework 4.6 and 4.5

Initializes a new instance of the StreamWriter class for the specified stream by using the specified encoding and buffer size, and optionally leaves the stream open.

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

public StreamWriter(
	Stream stream,
	Encoding encoding,
	int bufferSize,
	bool leaveOpen


Type: System.IO.Stream

The stream to write to.

Type: System.Text.Encoding

The character encoding to use.

Type: System.Int32

The buffer size, in bytes.

Type: System.Boolean

true to leave the stream open after the StreamWriter object is disposed; otherwise, false.

Exception Condition

stream or encoding is null.


bufferSize is negative.


stream is not writable.

Unless you set the leaveOpen parameter to true, the StreamWriter object calls Dispose() on the provided Stream object when StreamWriter.Dispose is called.

This constructor initializes the Encoding property by using the encoding parameter, and initializes the BaseStream property by using the stream parameter. The position of the stream is not reset. For additional information, see the Encoding property.


When you compile a set of characters with a particular cultural setting and retrieve those same characters with a different cultural setting, the characters might not be interpretable, and could cause an exception to be thrown.

The following example demonstrates this constructor.

using System;
using System.IO;
using System.Text;

namespace ConsoleApplication
    class Program
        static void Main(string[] args)
            string fileName = "test.txt";
            string textToAdd = "Example text in file";
            FileStream fs = null;
                fs = new FileStream(fileName, FileMode.CreateNew);
                using (StreamWriter writer = new StreamWriter(fs, Encoding.UTF8, 512, false))
                if (fs != null)

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 4.5
Portable Class Library
Supported in: portable .NET platforms
Windows Phone Silverlight
Available since 8.0
Windows Phone
Available since 8.1
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