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TextReader Class

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

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

'Declaration
<SerializableAttribute> _
<ComVisibleAttribute(True)> _
Public MustInherit Class TextReader
	Inherits MarshalByRefObject
	Implements IDisposable
'Usage
Dim instance As TextReader

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

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.

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

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.

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

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

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 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

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