StreamReader Class (System.IO)

Collapse All

Language Filter

This page is specific to

Microsoft Visual Studio 2008/.NET Framework 3.5

Other versions are also available for the following:

.NET Framework Class Library

StreamReader Class

Updated: November 2007

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

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

Syntax

Visual Basic (Declaration)

<SerializableAttribute> _
<ComVisibleAttribute(True)> _
Public Class StreamReader _
    Inherits TextReader

Visual Basic (Usage)

Dim instance As StreamReader

[SerializableAttribute]
[ComVisibleAttribute(true)]
public class StreamReader : TextReader

Visual C++

[SerializableAttribute]
[ComVisibleAttribute(true)]
public ref class StreamReader : public TextReader

/** @attribute SerializableAttribute */ 
/** @attribute ComVisibleAttribute(true) */
public class StreamReader extends TextReader

JScript

public class StreamReader extends TextReader

Remarks

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.

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.

By default, a StreamReader is not thread safe. See TextReader..::.Synchronized for a thread-safe wrapper.

The Read(array<Char>[]()[], Int32, Int32) and Write(array<Char>[]()[], Int32, Int32) method overloads read and write the number of characters specified by the count parameter. These are to be distinguished from BufferedStream..::.Read and BufferedStream..::.Write, 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.

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.

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

Examples

The following code example uses a StreamReader object to read text from a file.

Visual Basic

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);
        }
    }
}

Visual C++

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 );
   }
}

import System.*;
import System.IO.*;

class Test
{
    public static void main(String[] args)
    {
        try {            
            // Create an instance of StreamReader to read from a file.
            // The using statement also closes the StreamReader.
            StreamReader sr = new 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()) != null) {
                    Console.WriteLine(line);
                }
            }
            finally {
                sr.Dispose();
            }            
        }
        catch (System.Exception e) {
            // Let the user know what went wrong.
            Console.WriteLine("The file could not be read:");
            Console.WriteLine(e.get_Message());
        }
    } //main
} //Test

Inheritance Hierarchy

System..::.Object
  System..::.MarshalByRefObject
    System.IO..::.TextReader
      System.IO..::.StreamReader

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.

Platforms

Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, 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

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.

Version Information