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StreamReader Constructor (String, Encoding, Boolean, Int32)

Initializes a new instance of the StreamReader class for the specified file name, with the specified character encoding, byte order mark detection option, and buffer size.

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

public StreamReader(
	string path,
	Encoding encoding,
	bool detectEncodingFromByteOrderMarks,
	int bufferSize
)

Parameters

path
Type: System.String

The complete file path to be read.

encoding
Type: System.Text.Encoding

The character encoding to use.

detectEncodingFromByteOrderMarks
Type: System.Boolean

Indicates whether to look for byte order marks at the beginning of the file.

bufferSize
Type: System.Int32

The minimum buffer size, in number of 16-bit characters.

ExceptionCondition
ArgumentException

path is an empty string ("").

ArgumentNullException

path or encoding is null.

FileNotFoundException

The file cannot be found.

DirectoryNotFoundException

The specified path is invalid, such as being on an unmapped drive.

NotSupportedException

path includes an incorrect or invalid syntax for file name, directory name, or volume label.

ArgumentOutOfRangeException

buffersize is less than or equal to zero.

This constructor initializes the encoding as specified by the encoding parameter.

This constructor allows you to change the encoding the first time you read from the StreamReader object. The detectEncodingFromByteOrderMarks parameter detects the encoding by looking at the first three bytes of the stream. It automatically recognizes UTF-8, little-endian Unicode, and big-endian Unicode text if the file starts with the appropriate byte order marks. Otherwise, the user-provided encoding is used. See the Encoding.GetPreamble method for more information.

The buffer size, in number of 16-bit characters, is set by the bufferSize parameter. If bufferSize is less than the minimum allowable size (128 characters), the minimum allowable size is used.

The path parameter can be a file name, including a file on a Universal Naming Convention (UNC) share.

The path parameter is not required to be a file stored on disk; it can be any part of a system that supports access using streams.

Caution noteCaution:

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.

For a list of common I/O tasks, see Common I/O Tasks.

The following code example demonstrates this StreamReader constructor.

private void getNewStreamReader() 
{
    //Get a new StreamReader in ASCII format from a 
    //file using a buffer and byte order mark detection
    StreamReader srAsciiFromFileFalse512 = 
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII, false, 512);
    //Get a new StreamReader in ASCII format from a 
    //file with byte order mark detection = false
    StreamReader srAsciiFromFileFalse = 
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII, false);
    //Get a new StreamReader in ASCII format from a file 
    StreamReader srAsciiFromFile = 
        new StreamReader("C:\\Temp\\Test.txt",
        System.Text.Encoding.ASCII);
    //Get a new StreamReader from a 
    //file with byte order mark detection = false
    StreamReader srFromFileFalse = 
        new StreamReader("C:\\Temp\\Test.txt", false);
    //Get a new StreamReader from a file
    StreamReader srFromFile = 
        new StreamReader("C:\\Temp\\Test.txt");
    //Get a new StreamReader in ASCII format from a 
    //FileStream with byte order mark detection = false and a buffer
    StreamReader srAsciiFromStreamFalse512 = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII, false, 512);
    //Get a new StreamReader in ASCII format from a 
    //FileStream with byte order mark detection = false
    StreamReader srAsciiFromStreamFalse = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII, false);
    //Get a new StreamReader in ASCII format from a FileStream
    StreamReader srAsciiFromStream = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"),
        System.Text.Encoding.ASCII);
    //Get a new StreamReader from a 
    //FileStream with byte order mark detection = false
    StreamReader srFromStreamFalse = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"), 
        false);
    //Get a new StreamReader from a FileStream
    StreamReader srFromStream = new StreamReader(
        (System.IO.Stream)File.OpenRead("C:\\Temp\\Test.txt"));
}

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

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