StreamReader Constructors

Definition

Namespace:

System.IO

Assemblies:

netstandard.dll, System.Runtime.dll

Initializes a new instance of the StreamReader class for the specified stream.

Overloads

StreamReader(Stream)	Initializes a new instance of the StreamReader class for the specified stream.
StreamReader(Stream, Encoding, Boolean, Int32, Boolean)	Initializes a new instance of the StreamReader class for the specified stream based on the specified character encoding, byte order mark detection option, and buffer size, and optionally leaves the stream open.
StreamReader(String, Encoding, Boolean, FileStreamOptions)	Initializes a new instance of the StreamReader class for the specified file path, with the specified character encoding, byte order mark detection option, and configured with the specified FileStreamOptions object.
StreamReader(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.
StreamReader(Stream, Encoding, Boolean, Int32)	Initializes a new instance of the StreamReader class for the specified stream, with the specified character encoding, byte order mark detection option, and buffer size.
StreamReader(Stream, Encoding, Boolean)	Initializes a new instance of the StreamReader class for the specified stream, with the specified character encoding and byte order mark detection option.
StreamReader(String, Encoding, Boolean)	Initializes a new instance of the StreamReader class for the specified file name, with the specified character encoding and byte order mark detection option.
StreamReader(String, FileStreamOptions)	Initializes a new instance of the StreamReader class for the specified file path, using the default encoding, enabling detection of byte order marks at the beginning of the file, and configured with the specified FileStreamOptions object.
StreamReader(String, Boolean)	Initializes a new instance of the StreamReader class for the specified file name, with the specified byte order mark detection option.
StreamReader(Stream, Encoding)	Initializes a new instance of the StreamReader class for the specified stream, with the specified character encoding.
StreamReader(Stream, Boolean)	Initializes a new instance of the StreamReader class for the specified stream, with the specified byte order mark detection option.
StreamReader(String)	Initializes a new instance of the StreamReader class for the specified file name.
StreamReader(String, Encoding)	Initializes a new instance of the StreamReader class for the specified file name, with the specified character encoding.

StreamReader(Stream)

Source:

StreamReader.cs

Initializes a new instance of the StreamReader class for the specified stream.

C#

public StreamReader(System.IO.Stream stream);

Parameters

stream

Stream

The stream to be read.

Exceptions

ArgumentException

stream does not support reading.

ArgumentNullException

stream is null.

Examples

The following code example demonstrates this StreamReader constructor.

C#

using System;
using System.IO;

class Test
{
    public static void Main()
    {
        string path = @"c:\temp\MyTest.txt";

        try
        {
            if (File.Exists(path))
            {
                File.Delete(path);
            }

            using (StreamWriter sw = new StreamWriter(new FileStream(path, FileMode.CreateNew)))
            {
                sw.WriteLine("This");
                sw.WriteLine("is some text");
                sw.WriteLine("to test");
                sw.WriteLine("reading");
            }

            using (StreamReader sr = new StreamReader(new FileStream(path, FileMode.Open)))
            {
                while (sr.Peek() >= 0)
                {
                    Console.WriteLine(sr.ReadLine());
                }
            }
        }
        catch (Exception e)
        {
            Console.WriteLine("The process failed: {0}", e.ToString());
        }
    }
}

Remarks

This constructor initializes the encoding to UTF8Encoding, the BaseStream property using the stream parameter, and the internal buffer size to 1024 bytes.

The StreamReader object calls Dispose() on the provided Stream object when StreamReader.Dispose is called.

Caution

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.

See also

• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

StreamReader(Stream, Encoding, Boolean, Int32, Boolean)

Source:

StreamReader.cs

Initializes a new instance of the StreamReader class for the specified stream based on the specified character encoding, byte order mark detection option, and buffer size, and optionally leaves the stream open.

C#

public StreamReader(System.IO.Stream stream, System.Text.Encoding? encoding = default, bool detectEncodingFromByteOrderMarks = true, int bufferSize = -1, bool leaveOpen = false);

Parameters

stream

Stream

The stream to read.

encoding

Encoding

The character encoding to use.

detectEncodingFromByteOrderMarks

Boolean

true to look for byte order marks at the beginning of the file; otherwise, false.

bufferSize

Int32

The minimum buffer size.

leaveOpen

Boolean

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

Remarks

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

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.

This constructor enables you to change the encoding the first time you read from the StreamReader object. If the detectEncodingFromByteOrderMarks parameter is true, the constructor detects the encoding by looking at the first four bytes of the stream. It automatically recognizes UTF-8, little-endian UTF-16, big-endian UTF-16, little-endian UTF-32, and big-endian UTF-32 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.

Note

When reading from a Stream, it is more efficient to use a buffer that is the same size as the internal buffer of the stream.

Caution

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 interpreted correctly, and could cause an exception to be thrown.

StreamReader(String, Encoding, Boolean, FileStreamOptions)

Source:

StreamReader.cs

Initializes a new instance of the StreamReader class for the specified file path, with the specified character encoding, byte order mark detection option, and configured with the specified FileStreamOptions object.

C#

public StreamReader(string path, System.Text.Encoding encoding, bool detectEncodingFromByteOrderMarks, System.IO.FileStreamOptions options);

Parameters

path

String

The complete file path to be read.

encoding

Encoding

The character encoding to use.

detectEncodingFromByteOrderMarks

Boolean

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

options

FileStreamOptions

An object that specifies the configuration options for the underlying FileStream.

Exceptions

ArgumentException

path is not readable.

      -or-

path is an empty string ("").

ArgumentNullException

path or encoding or options 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.

See also

• Encoding
• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

StreamReader(String, Encoding, Boolean, Int32)

Source:

StreamReader.cs

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.

C#

public StreamReader(string path, System.Text.Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize);

Parameters

path

String

The complete file path to be read.

encoding

Encoding

The character encoding to use.

detectEncodingFromByteOrderMarks

Boolean

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

bufferSize

Int32

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

Exceptions

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.

Examples

The following code example demonstrates this StreamReader constructor.

C#

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"));
}

Remarks

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 four bytes of the stream. It automatically recognizes UTF-8, little-endian UTF-16, big-endian UTF-16, little-endian UTF-32, and big-endian UTF-32 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

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.

See also

• Encoding
• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

StreamReader(Stream, Encoding, Boolean, Int32)

Source:

StreamReader.cs

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

C#

public StreamReader(System.IO.Stream stream, System.Text.Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize);

Parameters

stream

Stream

The stream to be read.

encoding

Encoding

The character encoding to use.

detectEncodingFromByteOrderMarks

Boolean

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

bufferSize

Int32

The minimum buffer size.

Exceptions

ArgumentException

The stream does not support reading.

ArgumentNullException

stream or encoding is null.

ArgumentOutOfRangeException

bufferSize is less than or equal to zero.

Examples

The following code example demonstrates this StreamReader constructor.

C#

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"));
}

Remarks

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.

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 four bytes of the stream. It automatically recognizes UTF-8, little-endian UTF-16, big-endian UTF-16, little-endian UTF-32, and big-endian UTF-32 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 StreamReader object calls Dispose() on the provided Stream object when StreamReader.Dispose is called.

Note

When reading from a Stream, it is more efficient to use a buffer that is the same size as the internal buffer of the stream.

Caution

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.

See also

• Encoding
• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

StreamReader(Stream, Encoding, Boolean)

Source:

StreamReader.cs

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

C#

public StreamReader(System.IO.Stream stream, System.Text.Encoding encoding, bool detectEncodingFromByteOrderMarks);

Parameters

stream

Stream

The stream to be read.

encoding

Encoding

The character encoding to use.

detectEncodingFromByteOrderMarks

Boolean

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

Exceptions

ArgumentException

stream does not support reading.

ArgumentNullException

stream or encoding is null.

Examples

The following code example demonstrates this StreamReader constructor.

C#

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"));
}

Remarks

This constructor initializes the encoding as specified by the encoding parameter, the BaseStream property using the stream parameter, and the internal buffer size to 1024 bytes.

The detectEncodingFromByteOrderMarks parameter detects the encoding by looking at the first four bytes of the stream. It automatically recognizes UTF-8, little-endian UTF-16, big-endian UTF-16, little-endian UTF-32, and big-endian UTF-32 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 StreamReader object calls Dispose() on the provided Stream object when StreamReader.Dispose is called.

Caution

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.

See also

• Encoding
• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

StreamReader(String, Encoding, Boolean)

Source:

StreamReader.cs

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

C#

public StreamReader(string path, System.Text.Encoding encoding, bool detectEncodingFromByteOrderMarks);

Parameters

path

String

The complete file path to be read.

encoding

Encoding

The character encoding to use.

detectEncodingFromByteOrderMarks

Boolean

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

Exceptions

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.

Examples

The following code example demonstrates this StreamReader constructor.

C#

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"));
}

Remarks

This constructor initializes the encoding as specified by the encoding parameter, and the internal buffer size to 1024 bytes.

The detectEncodingFromByteOrderMarks parameter detects the encoding by looking at the first four bytes of the stream. It automatically recognizes UTF-8, little-endian UTF-16, big-endian UTF-16, little-endian UTF-32, and big-endian UTF-32 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 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

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.

See also

• Encoding
• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

StreamReader(String, FileStreamOptions)

Source:

StreamReader.cs

Initializes a new instance of the StreamReader class for the specified file path, using the default encoding, enabling detection of byte order marks at the beginning of the file, and configured with the specified FileStreamOptions object.

C#

public StreamReader(string path, System.IO.FileStreamOptions options);

Parameters

path

String

The complete file path to be read.

options

FileStreamOptions

An object that specifies the configuration options for the underlying FileStream.

Exceptions

ArgumentException

path is not readable.

-or-

      <code data-dev-comment-type="paramref">path</code> is an empty string ("").

ArgumentNullException

path or options is null.

FileNotFoundException

The file cannot be found.

DirectoryNotFoundException

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

IOException

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

See also

• Encoding
• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

StreamReader(String, Boolean)

Source:

StreamReader.cs

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

C#

public StreamReader(string path, bool detectEncodingFromByteOrderMarks);

Parameters

path

String

The complete file path to be read.

detectEncodingFromByteOrderMarks

Boolean

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

Exceptions

ArgumentException

path is an empty string ("").

ArgumentNullException

path is null.

FileNotFoundException

The file cannot be found.

DirectoryNotFoundException

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

IOException

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

Examples

The following code example demonstrates this StreamReader constructor.

C#

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"));
}

Remarks

This constructor initializes the encoding to UTF8Encoding, the BaseStream property using the stream parameter, and the internal buffer size to 1024 bytes.

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.

The detectEncodingFromByteOrderMarks parameter detects the encoding by looking at the first four bytes of the stream. It automatically recognizes UTF-8, little-endian UTF-16, big-endian UTF-16, little-endian UTF-32, and big-endian UTF-32 text if the file starts with the appropriate byte order marks. Otherwise, the UTF8Encoding is used. See the Encoding.GetPreamble method for more information.

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

See also

• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

StreamReader(Stream, Encoding)

Source:

StreamReader.cs

Initializes a new instance of the StreamReader class for the specified stream, with the specified character encoding.

C#

public StreamReader(System.IO.Stream stream, System.Text.Encoding encoding);

Parameters

stream

Stream

The stream to be read.

encoding

Encoding

The character encoding to use.

Exceptions

ArgumentException

stream does not support reading.

ArgumentNullException

stream or encoding is null.

Examples

The following code example demonstrates this StreamReader constructor.

C#

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"));
}

Remarks

The character encoding is set by the encoding parameter, and the buffer size is set to 1024 bytes. The StreamReader object attempts to detect the encoding by looking at the first four bytes of the stream. It automatically recognizes UTF-8, little-endian UTF-16, big-endian UTF-16, little-endian UTF-32, and big-endian UTF-32 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 StreamReader object calls Dispose() on the provided Stream object when StreamReader.Dispose is called.

Caution

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.

See also

• Encoding
• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

StreamReader(Stream, Boolean)

Source:

StreamReader.cs

Initializes a new instance of the StreamReader class for the specified stream, with the specified byte order mark detection option.

C#

public StreamReader(System.IO.Stream stream, bool detectEncodingFromByteOrderMarks);

Parameters

stream

Stream

The stream to be read.

detectEncodingFromByteOrderMarks

Boolean

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

Exceptions

ArgumentException

stream does not support reading.

ArgumentNullException

stream is null.

Examples

The following code example demonstrates this StreamReader constructor.

C#

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"));
}

Remarks

This constructor initializes the encoding to UTF8Encoding, the BaseStream property using the stream parameter, and the internal buffer size to 1024 bytes.

The detectEncodingFromByteOrderMarks parameter detects the encoding by looking at the first four bytes of the stream. It automatically recognizes UTF-8, little-endian UTF-16, big-endian UTF-16, little-endian UTF-32, and big-endian UTF-32 text if the file starts with the appropriate byte order marks. See the Encoding.GetPreamble method for more information.

The StreamReader object calls Dispose() on the provided Stream object when StreamReader.Dispose is called.

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

See also

• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

StreamReader(String)

Source:

StreamReader.cs

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

C#

public StreamReader(string path);

Parameters

path

String

The complete file path to be read.

Exceptions

ArgumentException

path is an empty string ("").

ArgumentNullException

path is null.

FileNotFoundException

The file cannot be found.

DirectoryNotFoundException

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

IOException

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

Examples

The following code example demonstrates this StreamReader constructor.

C#

using System;
using System.IO;

class Test
{
    
    public static void Main()
    {
        string path = @"c:\temp\MyTest.txt";

        try
        {
            if (File.Exists(path))
            {
                File.Delete(path);
            }

            using (StreamWriter sw = new StreamWriter(path))
            {
                sw.WriteLine("This");
                sw.WriteLine("is some text");
                sw.WriteLine("to test");
                sw.WriteLine("Reading");
            }

            using (StreamReader sr = new StreamReader(path))
            {
                while (sr.Peek() >= 0)
                {
                    Console.WriteLine(sr.ReadLine());
                }
            }
        }
        catch (Exception e)
        {
            Console.WriteLine("The process failed: {0}", e.ToString());
        }
    }
}

Remarks

The complete file path is specified by the path parameter. This constructor initializes the encoding to UTF8Encoding and the buffer size to 1024 bytes.

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

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.

See also

• Encoding
• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File

StreamReader(String, Encoding)

Source:

StreamReader.cs

Initializes a new instance of the StreamReader class for the specified file name, with the specified character encoding.

C#

public StreamReader(string path, System.Text.Encoding encoding);

Parameters

path

String

The complete file path to be read.

encoding

Encoding

The character encoding to use.

Exceptions

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.

Examples

The following code example demonstrates this StreamReader constructor.

C#

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"));
}

Remarks

This constructor initializes the encoding as specified by the encoding parameter, and the internal buffer size to 1024 bytes. The StreamReader object attempts to detect the encoding by looking at the first four bytes of the stream. It automatically recognizes UTF-8, little-endian UTF-16, big-endian UTF-16, little-endian UTF-32, and big-endian UTF-32 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 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

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.

See also

• Encoding
• File and Stream I/O
• How to: Read Text from a File
• How to: Write Text to a File