StreamReader Class

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

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

public class StreamReader : TextReader

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(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 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.


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.

The following example uses an instance of StreamReader to read text from a file.

using System;
using System.IO;

class Test 
    public static void Main() 
            // 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) 
        catch (Exception e) 
            // Let the user know what went wrong.
            Console.WriteLine("The file could not be read:");

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, 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, Zune

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.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0