TextReader Class (System.IO)

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Microsoft Visual Studio 2008/.NET Framework 3.5

Other versions are also available for the following:

.NET Framework Class Library

TextReader Class

Updated: November 2007

Represents a reader that can read a sequential series of characters.

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

Syntax

Visual Basic (Declaration)

<SerializableAttribute> _
<ComVisibleAttribute(True)> _
Public MustInherit Class TextReader _
    Inherits MarshalByRefObject _
    Implements IDisposable

Visual Basic (Usage)

Dim instance As TextReader

[SerializableAttribute]
[ComVisibleAttribute(true)]
public abstract class TextReader : MarshalByRefObject, 
    IDisposable

Visual C++

[SerializableAttribute]
[ComVisibleAttribute(true)]
public ref class TextReader abstract : public MarshalByRefObject, 
    IDisposable

/** @attribute SerializableAttribute */ 
/** @attribute ComVisibleAttribute(true) */
public abstract class TextReader extends MarshalByRefObject implements IDisposable

JScript

public abstract class TextReader extends MarshalByRefObject implements IDisposable

Remarks

TextReader is the abstract base class of StreamReader and StringReader, which read characters from streams and strings, respectively. Use these derived classes to open a text file for reading a specified range of characters, or to create a reader based on an existing stream.

Notes to Inheritors:

A derived class must minimally implement the Peek and Read methods to make a useful instance of TextReader.

Examples

The following code example demonstrates the polymorphic behavior of the TextReader and TextWriter types. Since aStringWriter and aStreamWriter are both TextWriter types, the WriteVowel method is called with both objects and the Write methods associated with each specific type are executed. Similarly, the ReadText method is called with both aStringReader and aStreamReader, and the correct ReadToEnd method is executed. Note that for aStringWriter and aStringReader, the backing store is a string, while a file is the backing store for aStreamWriter and aStreamReader.

Visual Basic

Imports System
Imports System.IO

Public Class TextRW

    Shared Sub Main()
        Dim aStringWriter, aStreamWriter As TextWriter
        aStringWriter = New StringWriter()
        aStreamWriter = New StreamWriter("InvalidPathChars.txt")

        WriteText(aStringWriter)
        WriteText(aStreamWriter)
        aStreamWriter.Close()

        Dim aStringReader, aStreamReader As TextReader
        aStringReader = New StringReader(aStringWriter.ToString())
        aStreamReader = New StreamReader("InvalidPathChars.txt")

        ReadText(aStringReader)
        ReadText(aStreamReader)
        aStreamReader.Close()
    End Sub

    Shared Sub WriteText(aTextWriter As TextWriter)
        aTextWriter.Write("Invalid file path characters are: ")
        aTextWriter.Write(Path.InvalidPathChars)
        aTextWriter.Write("."C)
    End Sub

    Shared Sub ReadText(aTextReader As TextReader)
        Console.WriteLine("From {0} - {1}", _
            aTextReader.GetType().Name, aTextReader.ReadToEnd())
    End Sub

End Class

using System;
using System.IO;

class TextRW
{
    static void Main()
    {
        TextWriter stringWriter = new StringWriter();
        using(TextWriter streamWriter = 
            new StreamWriter("InvalidPathChars.txt"))
        {
            WriteText(stringWriter);
            WriteText(streamWriter);
        }

        TextReader stringReader = 
            new StringReader(stringWriter.ToString());
        using(TextReader streamReader = 
            new StreamReader("InvalidPathChars.txt"))
        {
            ReadText(stringReader);
            ReadText(streamReader);
        }
    }

    static void WriteText(TextWriter textWriter)
    {
        textWriter.Write("Invalid file path characters are: ");
        textWriter.Write(Path.InvalidPathChars);
        textWriter.Write('.');
    }

    static void ReadText(TextReader textReader)
    {
        Console.WriteLine("From {0} - {1}", 
            textReader.GetType().Name, textReader.ReadToEnd());
    }
}

Visual C++

using namespace System;
using namespace System::IO;

void WriteText( TextWriter^ textWriter )
{
   textWriter->Write(  "Invalid file path characters are: " );
   textWriter->Write( Path::InvalidPathChars );
   textWriter->Write( Char::Parse( "." ) );
}


void ReadText( TextReader^ textReader )
{
   Console::WriteLine( "From {0} - {1}", textReader->GetType()->Name, textReader->ReadToEnd() );
}


int main()
{

   TextWriter^ stringWriter = gcnew StringWriter;
   TextWriter^ streamWriter = gcnew StreamWriter(  "InvalidPathChars.txt" );

   WriteText( stringWriter );
   WriteText( streamWriter );
   streamWriter->Close();

   TextReader^ stringReader = gcnew StringReader( stringWriter->ToString() );
   TextReader^ streamReader = gcnew StreamReader(  "InvalidPathChars.txt" );

   ReadText( stringReader );
   ReadText( streamReader );
   streamReader->Close();
}

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

class TextRW
{
    public static void main(String[] args)
    {
        TextWriter stringWriter = new StringWriter();
        TextWriter streamWriter = new StreamWriter("InvalidPathChars.txt");
        try {
            WriteText(stringWriter);
            WriteText(streamWriter);
        }
        finally {
            streamWriter.Dispose();
        }
        TextReader stringReader = new StringReader(stringWriter.ToString());
        TextReader streamReader = new StreamReader("InvalidPathChars.txt");
        try {
            ReadText(stringReader);
            ReadText(streamReader);
        }
        finally {
            streamReader.Dispose();
        }        
    } //main

    static void WriteText(TextWriter textWriter)
    {
        textWriter.Write("Invalid file path characters are: ");
        textWriter.Write(Path.InvalidPathChars);
        textWriter.Write('.');
    } //WriteText

    static void ReadText(TextReader textReader) 
    {
        Console.WriteLine("From {0} - {1}", 
            textReader.GetType().get_Name(),textReader.ReadToEnd());
    } //ReadText
} //TextRW

Inheritance Hierarchy

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

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