TextReader Class

Namespace: System.IO
Assembly: System.dll

Represents an abstract base class for all text readers, providing a common, simple contract for reading characters from a sequential source of characters. The TextReader class is the abstract base class for all readers that read strings. The StringReader class is derived from TextReader and reads from a string. The StreamReader class is also derived from TextReader and reads from a stream.

Inheritance

Object → TextReader

Remarks

The TextReader class provides a base class for reading text. It supports reading characters one at a time, a string of characters, or an array of characters. The TextReader class also provides methods for detecting the end of a stream and for closing the reader.

When you derive a class from TextReader, you must override the following abstract members: Read(), Peek(), and ReadBlock(char[] buffer, int index, int count).

The Dispose() method is called automatically when a TextReader is no longer needed. You can override the Dispose(bool disposing) method to perform additional cleanup if necessary.

Members

Fields >

Null public static readonly TextReader Null
Returns a TextReader that has no characters available.

Properties >

Disposed protected bool Disposed
Indicates whether the TextReader object has been disposed of.
LineNumber public virtual int LineNumber { get; }
Gets the current line number.
LinePosition public virtual int LinePosition { get; }
Gets the current line position.

Methods >

Close public virtual void Close()
Closes the TextReader and releases any system resources associated with the reader.
Dispose public void Dispose()
Releases all resources used by the current instance of the TextReader class.
Read public abstract int Read()
Reads the next character and advances the character or stream position.
Read public virtual int Read(char[] buffer, int index, int count)
Reads a maximum of count characters from the current stream and writes them to buffer starting at index. Returns the number of characters read.
ReadBlock public virtual int ReadBlock(char[] buffer, int index, int count)
Reads a block of characters from the current reader and advances the position within the read data.
ReadAll public string ReadAll()
Reads all characters from the current position to the end of the stream and returns them as a string.
ReadLine public virtual string ReadLine()
Reads a line of characters from the current stream and returns the data as a string.
ReadPastNewline protected virtual int ReadPastNewline()
Reads past the next newline character.
ReadUrl public string ReadUrl()
Reads all characters from the current position to the end of the stream and returns them as a string. Deprecated.
Peek public abstract int Peek()
Returns the next character without consuming it or the character or stream position.
ConvertToString protected string ConvertToString(char[] buffer)
Converts a character array to a string.
Skip public virtual long Skip(long unicodeCharCount)
Skips the specified number of characters.

Protected Methods >

Dispose protected virtual void Dispose(bool disposing)
Releases the unmanaged resources used by the TextReader and optionally releases the managed resources.

Example

Reading from a String

This example demonstrates how to use the StringReader (a concrete implementation of TextReader) to read from a string.

using System;
using System.IO;

public class Example
{
    public static void Main()
    {
        string text = "Hello, World!\nThis is a test.";

        using (StringReader reader = new StringReader(text))
        {
            string line;
            while ((line = reader.ReadLine()) != null)
            {
                Console.WriteLine(line);
            }
        }
    }
}

Output:

Hello, World!
This is a test.

Reading from a File

This example demonstrates using StreamReader (another implementation of TextReader) to read a file line by line.

using System;
using System.IO;

public class FileReadExample
{
    public static void Main()
    {
        string filePath = "my_document.txt"; // Assume this file exists

        // Create a dummy file for demonstration
        File.WriteAllText(filePath, "First line of the file.\nSecond line.\nThird and final line.");

        try
        {
            using (StreamReader reader = new StreamReader(filePath))
            {
                string line;
                while ((line = reader.ReadLine()) != null)
                {
                    Console.WriteLine(line);
                }
            }
        }
        catch (FileNotFoundException)
        {
            Console.WriteLine($"Error: The file '{filePath}' was not found.");
        }
        catch (IOException ex)
        {
            Console.WriteLine($"An I/O error occurred: {ex.Message}");
        }
        finally
        {
            // Clean up the dummy file
            if (File.Exists(filePath))
            {
                File.Delete(filePath);
            }
        }
    }
}

Assumed Content of my_document.txt:

First line of the file.
Second line.
Third and final line.

Output:

First line of the file.
Second line.
Third and final line.