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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)

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

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

NameDescription
System_CAPS_protmethodTextReader()

Initializes a new instance of the TextReader class.

NameDescription
System_CAPS_pubmethodClose()

Closes the TextReader and releases any system resources associated with the TextReader.

System_CAPS_pubmethodCreateObjRef(Type)

Creates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object.(Inherited from MarshalByRefObject.)

System_CAPS_pubmethodDispose()

Releases all resources used by the TextReader object.

System_CAPS_protmethodDispose(Boolean)

Releases the unmanaged resources used by the TextReader and optionally releases the managed resources.

System_CAPS_pubmethodEquals(Object)

Determines whether the specified object is equal to the current object.(Inherited from Object.)

System_CAPS_protmethodFinalize()

Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)

System_CAPS_pubmethodGetHashCode()

Serves as the default hash function. (Inherited from Object.)

System_CAPS_pubmethodGetLifetimeService()

Retrieves the current lifetime service object that controls the lifetime policy for this instance.(Inherited from MarshalByRefObject.)

System_CAPS_pubmethodGetType()

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_pubmethodInitializeLifetimeService()

Obtains a lifetime service object to control the lifetime policy for this instance.(Inherited from MarshalByRefObject.)

System_CAPS_protmethodMemberwiseClone()

Creates a shallow copy of the current Object.(Inherited from Object.)

System_CAPS_protmethodMemberwiseClone(Boolean)

Creates a shallow copy of the current MarshalByRefObject object.(Inherited from MarshalByRefObject.)

System_CAPS_pubmethodPeek()

Reads 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.

System_CAPS_pubmethodRead()

Reads the next character from the text reader and advances the character position by one character.

System_CAPS_pubmethodRead(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.

System_CAPS_pubmethodReadAsync(Char[], Int32, Int32)

Reads a specified maximum number of characters from the current text reader asynchronously and writes the data to a buffer, beginning at the specified index.

System_CAPS_pubmethodReadBlock(Char[], Int32, Int32)

Reads a specified maximum number of characters from the current text reader and writes the data to a buffer, beginning at the specified index.

System_CAPS_pubmethodReadBlockAsync(Char[], Int32, Int32)

Reads a specified maximum number of characters from the current text reader asynchronously and writes the data to a buffer, beginning at the specified index.

System_CAPS_pubmethodReadLine()

Reads a line of characters from the text reader and returns the data as a string.

System_CAPS_pubmethodReadLineAsync()

Reads a line of characters asynchronously and returns the data as a string.

System_CAPS_pubmethodReadToEnd()

Reads all characters from the current position to the end of the text reader and returns them as one string.

System_CAPS_pubmethodReadToEndAsync()

Reads all characters from the current position to the end of the text reader asynchronously and returns them as one string.

System_CAPS_pubmethodSystem_CAPS_staticSynchronized(TextReader)

Creates a thread-safe wrapper around the specified TextReader.

System_CAPS_pubmethodToString()

Returns a string that represents the current object.(Inherited from Object.)

NameDescription
System_CAPS_pubfieldSystem_CAPS_staticNull

Provides a TextReader with no data to read from.

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.

System_CAPS_importantImportant

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();
        }
    }
}

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1

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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