Introduction

In this tutorial, we will explore FileStream and StreamReader classes in .NET. These classes are used for reading from and writing to files. We will specifically learn how to handle larger files that don't fit into memory.

By the end of this tutorial, you will be able to:
* Understand the basics of FileStream and StreamReader classes
* Use FileStream and StreamReader to read and write data
* Handle large files efficiently

Prerequisites:
You should have a basic understanding of C# and .NET framework.

Step-by-Step Guide

FileStream and StreamReader are part of the System.IO namespace in .NET. FileStream is used to read from and write to any location in a file. StreamReader is used for reading characters from a byte stream.

FileStream:
FileStream allows you to move forwards and backwards in a file. It can be used with Read, Write, CopyTo, and other methods.

StreamReader:
StreamReader is designed to read from a byte stream. It can handle character encoding automatically and can read from a binary stream.

Best Practices:
* Always close your streams. This can be done manually with the Close method, or automatically with the using keyword.
* Handle exceptions. File operations can fail for many reasons, so always put your code inside a try/catch block.

Code Examples

Example 1: Reading a file with FileStream and StreamReader

using System;
using System.IO;

class Program
{
    static void Main()
    {
        using (FileStream fs = new FileStream("test.txt", FileMode.Open, FileAccess.Read))
        {
            using (StreamReader sr = new StreamReader(fs))
            {
                string line;
                while ((line = sr.ReadLine()) != null)
                {
                    Console.WriteLine(line);
                }
            }
        }
    }
}

In this example, we first create a FileStream fs to open the file test.txt. Then, we create a StreamReader sr to read from this FileStream. The ReadLine method is used to read the file line by line. If the line is not null, we print it to the console.

Example 2: Writing to a file with FileStream

using System;
using System.IO;

class Program
{
    static void Main()
    {
        using (FileStream fs = new FileStream("test.txt", FileMode.Create, FileAccess.Write))
        {
            byte[] info = new System.Text.UTF8Encoding(true).GetBytes("This is some text in the file.");
            fs.Write(info, 0, info.Length);
        }
    }
}

In this example, we first create a FileStream fs to create and write to the file test.txt. We then write the byte array info to the file using the Write method.

Summary

In this tutorial, we have learned about the FileStream and StreamReader classes in .NET. We've seen how to use these classes to read from and write to files, and how to handle large files that don't fit into memory.

You can continue learning by exploring other classes in the System.IO namespace, such as StreamWriter and MemoryStream.

Practice Exercises

Exercise 1:
Create a program that reads a text file and counts the number of lines in the file.

Exercise 2:
Create a program that writes an array of strings to a text file, with each string on a new line.

Exercise 3:
Create a program that reads a large text file and writes its contents to another file in reverse order (last line first).

Tips for further practice:
Try to handle different types of data, such as binary data or encoded text. Try to handle exceptions and errors that may occur during file operations.