StreamReader Constructor (String, Encoding, Boolean, Int32)

StreamReader Constructor (String, Encoding, Boolean, Int32)

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

Initializes a new instance of the StreamReader class for the specified file name, using 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


Type: System.String
The complete file path to be read.
Type: System.Text.Encoding
The character encoding to use.
Type: System.Boolean
true to look for byte order marks at the beginning of the file; otherwise, false.
Type: System.Int32
The minimum buffer size, in number of 16-bit characters.


path is an empty string ("").


path or encoding is null.


The file cannot be found.


The specified path is invalid; for example, it might refer to an unmapped drive.


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


buffersize is less than or equal to zero.

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

This constructor enables 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.

Version Notes

Windows Phone

 This member has a SecurityCriticalAttribute attribute. This attribute restricts this member to internal use. Application code that uses this member throws a MethodAccessException.

Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

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