📚 File I/O with Streams in C# 📚

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🥔 What is File I/O?

File I/O (Input/Output) allows your C# program to read data from a file (input) or write data to a file (output).

➡️ Input – Taking data from a file and loading it into the program.
⬅️ Output – Writing data from the program to a file.

Think of it as reading a recipe from a book 📖 or writing your favorite potato recipe into your secret cookbook. 🍟🍴

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🎯 Why Use Streams?

A stream is like a pipeline that lets data flow between a file and your program. Imagine a stream of water carrying information back and forth. 💧📄

✅ Streams allow data to move smoothly between the source (file) and destination (program).
✅ You can read, write, or manipulate data using streams.

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🥔 Types of Streams in C#

C# provides different types of streams for different tasks:

🌊 Stream Type	📄 Purpose
FileStream	Read and write binary data to/from files.
StreamReader	Read text data from a file.
StreamWriter	Write text data to a file.
MemoryStream	Store data in memory temporarily.

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🎁 Let’s Explore with a Story!

🥔 PotatoScript wants to save her favorite potato recipes in a file and read them later. But this time, she wants to use streams to do the job efficiently! 🍲📚

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📝 Step 1: Using FileStream for Basic File Operations

FileStream is used for reading and writing binary data (such as images, videos, and other raw data) or text data.

📄 FileStream – Basic Syntax:

using System;
using System.IO;

class Program
{
    static void Main()
    {
        // Create a FileStream to write data
        using (FileStream fs = new FileStream("potato_recipes.txt", FileMode.Create))
        {
            byte[] data = System.Text.Encoding.UTF8.GetBytes("🥔 Potato Fries\n🥔 Mashed Potatoes\n🥔 Potato Salad");
            fs.Write(data, 0, data.Length);
            Console.WriteLine("Recipes have been written to the file using FileStream! 📄");
        }
    }
}

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🧠 Explanation:

• FileStream opens or creates the file potato_recipes.txt.
• fs.Write() writes binary data to the file.
• Encoding.UTF8.GetBytes() converts the text to bytes before writing.
• using ensures that the stream is properly closed after the operation.

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🎁 Output:

Recipes have been written to the file using FileStream! 📄

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📄 Reading Data Using FileStream:

using System;
using System.IO;

class Program
{
    static void Main()
    {
        // Create a FileStream to read data
        using (FileStream fs = new FileStream("potato_recipes.txt", FileMode.Open))
        {
            byte[] data = new byte[fs.Length];
            fs.Read(data, 0, data.Length);
            string content = System.Text.Encoding.UTF8.GetString(data);
            Console.WriteLine("Here are the recipes:\n" + content);
        }
    }
}

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🎁 Output:

Here are the recipes:
🥔 Potato Fries
🥔 Mashed Potatoes
🥔 Potato Salad

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📝 Step 2: Reading and Writing with StreamReader and StreamWriter

If you’re working with text files, StreamReader and StreamWriter make it easier.

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✏️ Writing to a File with StreamWriter:

using System;
using System.IO;

class Program
{
    static void Main()
    {
        // Write to the file using StreamWriter
        using (StreamWriter writer = new StreamWriter("potato_notes.txt"))
        {
            writer.WriteLine("🥔 Remember to buy more potatoes!");
            writer.WriteLine("🥔 Try a new potato salad recipe.");
            Console.WriteLine("Notes have been written successfully! 📒");
        }
    }
}

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🧠 Explanation:

• StreamWriter writes text data to potato_notes.txt.
• writer.WriteLine() writes one line at a time.
• using ensures the file is closed after writing.

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🎁 Output:

Notes have been written successfully! 📒

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📄 Reading a File with StreamReader:

using System;
using System.IO;

class Program
{
    static void Main()
    {
        // Read data from the file using StreamReader
        using (StreamReader reader = new StreamReader("potato_notes.txt"))
        {
            string note;
            while ((note = reader.ReadLine()) != null)
            {
                Console.WriteLine("📌 " + note);
            }
        }
    }
}

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🎁 Output:

📌 🥔 Remember to buy more potatoes!
📌 🥔 Try a new potato salad recipe.

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📝 Step 3: Using MemoryStream for Temporary Data Storage

MemoryStream is used to store data temporarily in memory instead of writing to a file.

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📄 Writing to MemoryStream:

using System;
using System.IO;

class Program
{
    static void Main()
    {
        // Create a MemoryStream
        using (MemoryStream ms = new MemoryStream())
        {
            byte[] data = System.Text.Encoding.UTF8.GetBytes("🥔 Data stored in memory!");
            ms.Write(data, 0, data.Length);
            
            // Read the data back
            ms.Position = 0; // Reset the position to read from the beginning
            byte[] readData = new byte[ms.Length];
            ms.Read(readData, 0, readData.Length);
            
            string content = System.Text.Encoding.UTF8.GetString(readData);
            Console.WriteLine("Data from memory: " + content);
        }
    }
}

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🎁 Output:

Data from memory: 🥔 Data stored in memory!

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📝 Step 4: Appending Data Using StreamWriter

To add more data without deleting existing content, use StreamWriter in append mode.

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using System;
using System.IO;

class Program
{
    static void Main()
    {
        // Append data to the file
        using (StreamWriter writer = new StreamWriter("potato_notes.txt", true))
        {
            writer.WriteLine("🥔 Don't forget the garlic for mashed potatoes!");
            Console.WriteLine("New note added! 📝");
        }
    }
}

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🎁 Output:

New note added! 📝

Now potato_notes.txt contains:

🥔 Remember to buy more potatoes!
🥔 Try a new potato salad recipe.
🥔 Don't forget the garlic for mashed potatoes!

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📝 Step 5: Advanced File I/O with BufferedStream

BufferedStream improves read/write performance by reducing the number of I/O operations.

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📄 Writing Data Using BufferedStream:

using System;
using System.IO;

class Program
{
    static void Main()
    {
        using (FileStream fs = new FileStream("potato_data.txt", FileMode.Create))
        using (BufferedStream bs = new BufferedStream(fs))
        {
            byte[] data = System.Text.Encoding.UTF8.GetBytes("🥔 Buffered data for faster I/O!");
            bs.Write(data, 0, data.Length);
            Console.WriteLine("Buffered data written successfully! 🚀");
        }
    }
}

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📄 Reading Data Using BufferedStream:

using System;
using System.IO;

class Program
{
    static void Main()
    {
        using (FileStream fs = new FileStream("potato_data.txt", FileMode.Open))
        using (BufferedStream bs = new BufferedStream(fs))
        {
            byte[] data = new byte[fs.Length];
            bs.Read(data, 0, data.Length);
            string content = System.Text.Encoding.UTF8.GetString(data);
            Console.WriteLine("Buffered data read successfully: " + content);
        }
    }
}