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.NET Framework Class Library
StreamReader Class

Implements a TextReader that reads characters from a byte stream in a particular encoding.

To browse the .NET Framework source code for this type, see the Reference Source.

Namespace:   System.IO
Assemblies:   mscorlib (in mscorlib.dll)
  System.IO (in System.IO.dll)
Syntax
<[%$TOPIC/6aetdk20_en-us_VS_110_4_0_0_0_0%]> _
<[%$TOPIC/6aetdk20_en-us_VS_110_4_0_0_0_1%](True)> _
Public Class StreamReader _
	Inherits [%$TOPIC/6aetdk20_en-us_VS_110_4_0_0_0_2%]
[[%$TOPIC/6aetdk20_en-us_VS_110_4_0_1_0_0%]]
[[%$TOPIC/6aetdk20_en-us_VS_110_4_0_1_0_1%](true)]
public class StreamReader : [%$TOPIC/6aetdk20_en-us_VS_110_4_0_1_0_2%]
[[%$TOPIC/6aetdk20_en-us_VS_110_4_0_2_0_0%]]
[[%$TOPIC/6aetdk20_en-us_VS_110_4_0_2_0_1%](true)]
public ref class StreamReader : public [%$TOPIC/6aetdk20_en-us_VS_110_4_0_2_0_2%]
[<[%$TOPIC/6aetdk20_en-us_VS_110_4_0_3_0_0%]>]
[<[%$TOPIC/6aetdk20_en-us_VS_110_4_0_3_0_1%](true)>]
type StreamReader =  
    class 
        inherit [%$TOPIC/6aetdk20_en-us_VS_110_4_0_3_0_2%] 
    end
public class StreamReader extends [%$TOPIC/6aetdk20_en-us_VS_110_4_0_4_0_0%]

The StreamReader type exposes the following members.

Constructors
  NameDescription
Public method Supported by the XNA Framework Supported by Portable Class Library StreamReader(Stream)Initializes a new instance of the StreamReader class for the specified stream.
Public method Supported by the XNA Framework StreamReader(String)Initializes a new instance of the StreamReader class for the specified file name.
Public method Supported by the XNA Framework Supported by Portable Class Library StreamReader(Stream, Boolean)Initializes a new instance of the StreamReader class for the specified stream, with the specified byte order mark detection option.
Public method Supported by the XNA Framework Supported by Portable Class Library StreamReader(Stream, Encoding)Initializes a new instance of the StreamReader class for the specified stream, with the specified character encoding.
Public method Supported by the XNA Framework StreamReader(String, Boolean)Initializes a new instance of the StreamReader class for the specified file name, with the specified byte order mark detection option.
Public method Supported by the XNA Framework StreamReader(String, Encoding)Initializes a new instance of the StreamReader class for the specified file name, with the specified character encoding.
Public method Supported by the XNA Framework Supported by Portable Class Library 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.
Public method Supported by the XNA Framework 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.
Public method Supported by the XNA Framework Supported by Portable Class Library 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.
Public method Supported by the XNA Framework 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.
Public method 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.
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Properties
  NameDescription
Public property Supported by the XNA Framework Supported by Portable Class Library BaseStreamReturns the underlying stream.
Public property Supported by the XNA Framework Supported by Portable Class Library CurrentEncodingGets the current character encoding that the current StreamReader object is using.
Public property Supported by the XNA Framework Supported by Portable Class Library EndOfStreamGets a value that indicates whether the current stream position is at the end of the stream.
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Methods
  NameDescription
Public method Supported by the XNA Framework CloseCloses the StreamReader object and the underlying stream, and releases any system resources associated with the reader. (Overrides TextReaderClose.)
Public method CreateObjRefCreates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object. (Inherited from MarshalByRefObject.)
Public method Supported by the XNA Framework Supported by Portable Class Library DiscardBufferedDataClears the internal buffer.
Public method Supported by the XNA Framework Supported by Portable Class Library DisposeReleases all resources used by the TextReader object. (Inherited from TextReader.)
Protected method Supported by the XNA Framework Supported by Portable Class Library Dispose(Boolean)Closes the underlying stream, releases the unmanaged resources used by the StreamReader, and optionally releases the managed resources. (Overrides TextReaderDispose(Boolean).)
Public method Supported by the XNA Framework Supported by Portable Class Library Equals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Protected method Supported by the XNA Framework Supported by Portable Class Library FinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public method Supported by the XNA Framework Supported by Portable Class Library GetHashCodeServes as the default hash function. (Inherited from Object.)
Public method GetLifetimeServiceRetrieves the current lifetime service object that controls the lifetime policy for this instance. (Inherited from MarshalByRefObject.)
Public method Supported by the XNA Framework Supported by Portable Class Library GetTypeGets the Type of the current instance. (Inherited from Object.)
Public method InitializeLifetimeServiceObtains a lifetime service object to control the lifetime policy for this instance. (Inherited from MarshalByRefObject.)
Protected method Supported by the XNA Framework Supported by Portable Class Library MemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Protected method MemberwiseClone(Boolean)Creates a shallow copy of the current MarshalByRefObject object. (Inherited from MarshalByRefObject.)
Public method Supported by the XNA Framework Supported by Portable Class Library PeekReturns the next available character but does not consume it. (Overrides TextReaderPeek.)
Public method Supported by the XNA Framework Supported by Portable Class Library ReadReads the next character from the input stream and advances the character position by one character. (Overrides TextReaderRead.)
Public method Supported by the XNA Framework Supported by Portable Class Library Read(Char, Int32, Int32)Reads a specified maximum of characters from the current stream into a buffer, beginning at the specified index. (Overrides TextReaderRead(Char, Int32, Int32).)
Public method ReadAsyncReads a specified maximum number of characters from the current stream asynchronously and writes the data to a buffer, beginning at the specified index. (Overrides TextReaderReadAsync(Char, Int32, Int32).)
Public method Supported by the XNA Framework Supported by Portable Class Library ReadBlockReads a specified maximum number of characters from the current stream and writes the data to a buffer, beginning at the specified index. (Overrides TextReaderReadBlock(Char, Int32, Int32).)

In .NET Framework Client Profile 4, this member is inherited from TextReader ReadBlock(Char, Int32, Int32).


In XNA Framework 3.0, this member is inherited from TextReader ReadBlock(Char, Int32, Int32).


In Portable Class Library Portable Class Library, this member is inherited from TextReader ReadBlock(Char, Int32, Int32).
Public method ReadBlockAsyncReads a specified maximum number of characters from the current stream asynchronously and writes the data to a buffer, beginning at the specified index. (Overrides TextReaderReadBlockAsync(Char, Int32, Int32).)
Public method Supported by the XNA Framework Supported by Portable Class Library ReadLineReads a line of characters from the current stream and returns the data as a string. (Overrides TextReaderReadLine.)
Public method ReadLineAsyncReads a line of characters asynchronously from the current stream and returns the data as a string. (Overrides TextReaderReadLineAsync.)
Public method Supported by the XNA Framework Supported by Portable Class Library ReadToEndReads all characters from the current position to the end of the stream. (Overrides TextReaderReadToEnd.)
Public method ReadToEndAsyncReads all characters from the current position to the end of the stream asynchronously and returns them as one string. (Overrides TextReaderReadToEndAsync.)
Public method Supported by the XNA Framework Supported by Portable Class Library ToStringReturns a string that represents the current object. (Inherited from Object.)
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Fields
  NameDescription
Public field Static member Supported by the XNA Framework Supported by Portable Class Library NullA StreamReader object around an empty stream.
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Remarks
NoteNote

To view the .NET Framework source code for this type, see the Reference Source. You can browse through the source code online, download the reference for offline viewing, and step through the sources (including patches and updates) during debugging; see instructions.

StreamReader is designed for character input in a particular encoding, whereas the Stream class is designed for byte input and output. Use StreamReader for reading lines of information from a standard text file.

Important noteImportant

This type implements the IDisposable interface. When you have finished using the type, you should dispose of it either directly or indirectly. To dispose of the type directly, call its Dispose method in a try/catch block. To dispose of it indirectly, use a language construct such as using (in C#) or Using (in Visual Basic). For more information, see the “Using an Object that Implements IDisposable” section in the IDisposable interface topic.

StreamReader defaults to UTF-8 encoding unless specified otherwise, instead of defaulting to the ANSI code page for the current system. UTF-8 handles Unicode characters correctly and provides consistent results on localized versions of the operating system. If you get the current character encoding using the CurrentEncoding property, the value is not reliable until after the first Read method, since encoding auto detection is not done until the first call to a Read method.

By default, a StreamReader is not thread safe. See TextReaderSynchronized for a thread-safe wrapper.

The Read(Char, Int32, Int32) and Write(Char, Int32, Int32) method overloads read and write the number of characters specified by the count parameter. These are to be distinguished from BufferedStreamRead and BufferedStreamWrite, which read and write the number of bytes specified by the count parameter. Use the BufferedStream methods only for reading and writing an integral number of byte array elements.

NoteNote

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.

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

Examples

The following example uses an instance of StreamReader to read text from a file. The constructor used in this example is not supported for use in Windows Store Apps.

Imports System
Imports System.IO

Class Test
    Public Shared Sub Main()
        Try 
            ' Create an instance of StreamReader to read from a file. 
            Dim sr As StreamReader = New StreamReader("TestFile.txt")
            Dim line As String 
            ' Read and display the lines from the file until the end  
            ' of the file is reached. 
            Do
                line = sr.ReadLine()
                Console.WriteLine(Line)
            Loop Until line Is Nothing
            sr.Close()
        Catch E As Exception
            ' Let the user know what went wrong.
            Console.WriteLine("The file could not be read:")
            Console.WriteLine(E.Message)
        End Try 
    End Sub 
End Class
using System;
using System.IO;

class Test 
{
    public static void Main() 
    {
        try 
        {
            // Create an instance of StreamReader to read from a file. 
            // The using statement also closes the StreamReader. 
            using (StreamReader sr = new StreamReader("TestFile.txt")) 
            {
                string line;
                // Read and display lines from the file until the end of  
                // the file is reached. 
                while ((line = sr.ReadLine()) != null) 
                {
                    Console.WriteLine(line);
                }
            }
        }
        catch (Exception e) 
        {
            // Let the user know what went wrong.
            Console.WriteLine("The file could not be read:");
            Console.WriteLine(e.Message);
        }
    }
}
using namespace System;
using namespace System::IO;
int main()
{
   try
   {
      // Create an instance of StreamReader to read from a file.
      StreamReader^ sr = gcnew StreamReader( "TestFile.txt" );
      try
      {
         String^ line;

         // Read and display lines from the file until the end of  
         // the file is reached. 
         while ( line = sr->ReadLine() )
         {
            Console::WriteLine( line );
         }
      }
      finally
      {
         if ( sr )
            delete (IDisposable^)sr;
      }
   }
   catch ( Exception^ e ) 
   {
      // Let the user know what went wrong.
      Console::WriteLine( "The file could not be read:" );
      Console::WriteLine( e->Message );
   }
}

The following example instantiates a StreamReader object and calls its ReadAsync method to read a file asynchronously.

Imports System
Imports System.IO
Imports System.Threading.Tasks

Module Example
    Public Sub Main()
        ReadAndDisplayFilesAsync()
    End Sub 

    Private Async Sub ReadAndDisplayFilesAsync()
        Dim filename As String = "TestFile1.txt" 
        Dim buffer() As Char 

        Using sr As New StreamReader(filename)
            ReDim buffer(CInt(sr.BaseStream.Length))
            Await sr.ReadAsync(buffer, 0, CInt(sr.BaseStream.Length))
        End Using

        Console.WriteLine(New String(buffer))
    End Sub 
End Module 
' The example displays the following output: 
'       This is the first line of text in a relatively short file. 
'       This is the second line. 
'       This is the third line. 
'       This is the fourth and final line.
using System;
using System.IO;
using System.Threading.Tasks;

class Example
{
    public static void Main()
    {
        ReadAndDisplayFilesAsync();
    }

    private async static void ReadAndDisplayFilesAsync()
    {
        String filename = "TestFile1.txt";
        Char[] buffer;

        using (var sr = new StreamReader(filename)) {
            buffer = new Char[(int)sr.BaseStream.Length];
            await sr.ReadAsync(buffer, 0, (int)sr.BaseStream.Length);
        }

        Console.WriteLine(new String(buffer));
    }
}
// The example displays the following output: 
//       This is the first line of text in a relatively short file. 
//       This is the second line. 
//       This is the third line. 
//       This is the fourth and final line.
Version Information

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Portable Class Library

Supported in: Portable Class Library
Thread Safety
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.