StreamReader Constructor (String, Encoding, Boolean, Int32)

 
System_CAPS_noteNote

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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 Sub New (
	path As String,
	encoding As Encoding,
	detectEncodingFromByteOrderMarks As Boolean,
	bufferSize As Integer
)

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.

Exception Condition
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.

System_CAPS_cautionCaution

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 Sub getNewStreamReader()
    Dim S As Stream = File.OpenRead("C:\Temp\Test.txt")
    'Get a new StreamReader in ASCII format from a
    'file using a buffer and byte order mark detection
    Dim SrAsciiFromFileFalse512 As StreamReader = 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
    Dim SrAsciiFromFileFalse As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII, False)
    'Get a new StreamReader in ASCII format from a file 
    Dim SrAsciiFromFile As StreamReader = New StreamReader("C:\Temp\Test.txt", _
        System.Text.Encoding.ASCII)
    'Get a new StreamReader from a
    'file with byte order mark detection = false        
    Dim SrFromFileFalse As StreamReader = New StreamReader("C:\Temp\Test.txt", False)
    'Get a new StreamReader from a file
    Dim SrFromFile As StreamReader = 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
    Dim SrAsciiFromStreamFalse512 As StreamReader = New StreamReader(S, _
        System.Text.Encoding.ASCII, False, 512)
    'Get a new StreamReader in ASCII format from a
    'FileStream with byte order mark detection = false
    Dim SrAsciiFromStreamFalse = New StreamReader(S, _
        System.Text.Encoding.ASCII, False)
    'Get a new StreamReader in ASCII format from a FileStream
    Dim SrAsciiFromStream As StreamReader = New StreamReader(S, _
        System.Text.Encoding.ASCII)
    'Get a new StreamReader from a
    'FileStream with byte order mark detection = false
    Dim SrFromStreamFalse As StreamReader = New StreamReader(S, False)
    'Get a new StreamReader from a FileStream
    Dim SrFromStream As StreamReader = New StreamReader(S)

End Sub

.NET Framework
Available since 1.1
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
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