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StreamReader Class

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

For a list of all members of this type, see StreamReader Members.

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

[Visual Basic]
<Serializable>
Public Class StreamReader
   Inherits TextReader
[C#]
[Serializable]
public class StreamReader : TextReader
[C++]
[Serializable]
public __gc class StreamReader : public TextReader
[JScript]
public
   Serializable
class StreamReader extends TextReader

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.

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.

StreamReader.Read(Char[], Int32, Int32) and StreamWriter(Char[], Int32, Int32) 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 an example of using this class, see the Example section below. The following table lists examples of other typical or related I/O tasks.

To do this... See the example in this topic...
Create a text file. Writing Text to a File
Write to a text file. Writing Text to a File
Read from a text file. Reading Text from a File
Append text to a file. Opening and Appending to a Log File

File.AppendText

FileInfo.AppendText

Get the size of a file. FileInfo.Length
Get the attributes of a file. File.GetAttributes
Set the attributes of a file. File.SetAttributes
Determine if a file exists. File.Exists
Read from a binary file. Reading and Writing to a Newly Created Data File
Write to a binary file. Reading and Writing to a Newly Created Data File

Example

[Visual Basic, C#, C++] The following example uses an instance of StreamReader 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

[C#] 
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);
        }
    }
}

[C++] 
#using <mscorlib.dll>

using namespace System;
using namespace System::IO;

int main() {
    try {
        // Create an instance of StreamReader to read from a file.
        // The using statement also closes the StreamReader.
        StreamReader* sr = new StreamReader(S"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) __try_cast<IDisposable*>(sr)->Dispose();
        }
    } catch (Exception* e) {
        // Let the user know what went wrong.
        Console::WriteLine(S"The file could not be read:");
        Console::WriteLine(e->Message);
    }
}

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Namespace: System.IO

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework

Assembly: Mscorlib (in Mscorlib.dll)

See Also

StreamReader Members | System.IO Namespace | Encoding | Stream | StreamWriter | Working with I/O | Reading Text from a File | Writing Text to a File | Basic File I/O | Reading and Writing to a Newly Created Data File

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