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TextReader Class

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

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

public abstract class TextReader : IDisposable

The TextReader type exposes the following members.

  NameDescription
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsTextReaderInitializes a new instance of the TextReader class.
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  NameDescription
Public methodSupported by the XNA FrameworkCloseCloses the TextReader and releases any system resources associated with the TextReader.
Public methodCreateObjRefCreates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object. (Inherited from MarshalByRefObject.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsDispose()Releases all resources used by the TextReader object.
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsDispose(Boolean)Releases the unmanaged resources used by the TextReader and optionally releases the managed resources.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsEquals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsGetHashCodeServes as the default hash function. (Inherited from Object.)
Public methodGetLifetimeServiceRetrieves the current lifetime service object that controls the lifetime policy for this instance. (Inherited from MarshalByRefObject.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodInitializeLifetimeServiceObtains a lifetime service object to control the lifetime policy for this instance. (Inherited from MarshalByRefObject.)
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsMemberwiseClone()Creates a shallow copy of the current Object. (Inherited from Object.)
Protected methodMemberwiseClone(Boolean)Creates a shallow copy of the current MarshalByRefObject object. (Inherited from MarshalByRefObject.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsPeekReads the next character without changing the state of the reader or the character source. Returns the next available character without actually reading it from the reader.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsRead()Reads the next character from the text reader and advances the character position by one character.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsRead(Char[], Int32, Int32)Reads a specified maximum number of characters from the current reader and writes the data to a buffer, beginning at the specified index.
Public methodSupported in .NET for Windows Store appsReadAsyncReads a specified maximum number of characters from the current text reader asynchronously and writes the data to a buffer, beginning at the specified index.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsReadBlockReads a specified maximum number of characters from the current text reader and writes the data to a buffer, beginning at the specified index.
Public methodSupported in .NET for Windows Store appsReadBlockAsyncReads a specified maximum number of characters from the current text reader asynchronously and writes the data to a buffer, beginning at the specified index.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsReadLineReads a line of characters from the text reader and returns the data as a string.
Public methodSupported in .NET for Windows Store appsReadLineAsyncReads a line of characters asynchronously and returns the data as a string.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsReadToEndReads all characters from the current position to the end of the text reader and returns them as one string.
Public methodSupported in .NET for Windows Store appsReadToEndAsyncReads all characters from the current position to the end of the text reader asynchronously and returns them as one string.
Public methodStatic memberSupported by the XNA FrameworkSynchronizedCreates a thread-safe wrapper around the specified TextReader.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsToStringReturns a string that represents the current object. (Inherited from Object.)
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  NameDescription
Public fieldStatic memberSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsNullProvides a TextReader with no data to read from.
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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.

Important noteImportant

This type implements the IDisposable interface. When you have finished using any type that derives from this type, you should dispose of it either directly or indirectly. To dispose of the type directly, call its Dispose method in a try/catch block. To dispose of it indirectly, use a language construct such as using (in C#) or Using (in Visual Basic). For more information, see Dispose and the “Using an Object that Implements IDisposable” section in the IDisposable interface topic.

Notes to Inheritors

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

The TextReader class is an abstract class. Therefore, you do not instantiate it in your code. The StreamReader class derives from TextReader and provides implementations of the members for reading from a stream. The following example shows how to read all the characters in a file by using the StreamReader.ReadAsync(Char[], Int32, Int32) method. It checks whether each character is a letter, digit, or white space before adding the character to an instance of the StringBuilder class.

using System;
using System.Windows;
using System.IO;
using System.Text;

namespace WpfApplication
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private async void Button_Click_1(object sender, RoutedEventArgs e)
        {
            string filename = @"C:\Example\existingfile.txt";
            char[] result;
            StringBuilder builder = new StringBuilder();

            using (StreamReader reader = File.OpenText(filename))
            {
                result = new char[reader.BaseStream.Length];
                await reader.ReadAsync(result, 0, (int)reader.BaseStream.Length);
            }

            foreach (char c in result)
            {
                if (char.IsLetterOrDigit(c) || char.IsWhiteSpace(c))
                {
                    builder.Append(c);
                }
            }
            FileOutput.Text = builder.ToString();
        }
    }
}

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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