System.IO Namespace in C# - File Handling Made Easy

👋 Hey there! Ready to explore System.IO?

Imagine you want to store user data, logs, or game progress in your C# program. How do you do it? 🤔 You can’t just store everything in variables—they disappear when the program closes! That’s where System.IO comes in.

The System.IO namespace in C# provides classes and methods to work with files, directories, and streams. It helps you create, read, write, move, and delete files effortlessly. 🚀

🎯 What You Are Going to Learn in This Lesson:

✔️ Understand what the System.IO namespace is and why it’s important.
✔️ List of System.IO namespace: Classes, Methods, Properties, Events, and Exceptions.

📘 What is System.IO Namespace?

The System.IO namespace in C# is like your personal toolbox for handling files and data streams.

🛠️ It provides classes to create, read, write, and manage files and directories on your system. Whether you need to save a document, read a text file, or manage folders, System.IO has got you covered! It includes powerful classes like File, Directory, StreamReader, StreamWriter, TextReader, TextWriter, and many more.

🚀 You’ll use this namespace in real-world applications like logging systems, data storage, and file transfers. Stay tuned, because we’ll explore these in detail with fun and easy examples! 😎

The System.IO namespace provides classes and methods to handle files and directories in C#. With it, you can:

📁 Work with files – Create, read, write, append, and delete files.
📂 Manage directories – Create and delete folders.
📄 Read & write data streams – Handle large data efficiently.

It contains several useful classes that make file handling easy. Let’s explore them! 🚀

🚀 Common and Popular Classes in System.IO

Here are the most important classes in System.IO:

Class Name	What It Does (Easy Explanation)
`BinaryReader`	Reads data in binary format (like numbers and text) from a file or stream.
`BinaryWriter`	Writes data in binary format to a file or stream.
`BufferedStream`	Speeds up reading and writing by storing data temporarily.
`Directory`	Helps create, move, delete, and list folders.
`DirectoryInfo`	Gives more details about a folder and allows operations like renaming and deleting.
`DriveInfo`	Provides information about drives (like free space and type of drive).
`File`	Provides quick ways to create, delete, move, and copy files.
`FileInfo`	Gives detailed information about a file and allows changes to it.
`FileSystemInfo`	Base class for FileInfo and DirectoryInfo, provides common properties.
`FileStream`	Reads and writes data to a file, like opening a file in a text editor.
`MemoryStream`	Works like a file but stores data in memory instead of on disk.
`Path`	Helps work with file and folder paths, like extracting file names and extensions.
`StreamReader`	Reads text from files easily.
`StreamWriter`	Writes text into files easily.
`TextReader`	Reads text from any input source (base class of StreamReader and StringReader).
`TextWriter`	Writes text to any output source (base class of StreamWriter and StringWriter).
`StringReader`	Reads text from a string, like reading a file but in memory.
`StringWriter`	Writes text into a string, like saving content before writing it to a file.
`FileSystemWatcher`	Monitors folders and files for any changes (like new files or deletions).

🔎 Common Properties in System.IO

Properties help get useful details about files, folders, and drives.

Class Name	Property Name	What It Does (Easy Explanation)
`FileInfo`	`Length`	Shows the file size (in bytes).
`FileInfo`	`DirectoryName`	Tells which folder the file is inside.
`DirectoryInfo`	`Parent`	Shows the parent folder (where the current folder is located).
`DirectoryInfo`	`Root`	Tells the main root folder (like C:\ on Windows).
`DriveInfo`	`AvailableFreeSpace`	Shows how much free space is left.
`DriveInfo`	`DriveType`	Tells if it’s a Hard Drive, SSD, or USB.
`DriveInfo`	`IsReady`	Checks if the drive is connected.
`Path`	`DirectorySeparatorChar`	Shows the slash (/ or \) used in file paths.
`Path`	`PathSeparator`	Shows the character used to separate paths in system variables.
`FileSystemInfo`	`Exists`	Checks if a file or folder exists.
`FileSystemInfo`	`FullName`	Returns the full path of a file or folder.

🛠 Common Methods in System.IO

Methods allow you to perform actions like creating, deleting, or modifying files, folders, and text.

Class Name	Method Name	What It Does (Easy Explanation)
`FileInfo`	`Create()`	Makes a new empty file.
	`Delete()`	Removes a file forever.
	`CopyTo("newPath")`	Copies a file to another location.
	`MoveTo("newPath")`	Moves a file to another folder.
`DirectoryInfo`	`Create()`	Makes a new folder.
	`Delete(true/false)`	Deletes a folder (if true, deletes everything inside too).
	`GetFiles()`	Lists all files inside a folder.
	`GetDirectories()`	Lists all subfolders inside a folder.
`DriveInfo`	`GetDrives()`	Lists all available drives on the system.
`Path`	`Combine("folder", "file.txt")`	Joins folder and file names into a full path.
	`GetExtension("file.txt")`	Gets the file extension (.txt, .jpg, etc.).
	`GetFileName("C:\Docs\file.txt")`	Extracts just the file name (file.txt).
`StreamReader`	`ReadToEnd()`	Reads the whole file as text.
`StreamWriter`	`Write("Hello!")`	Writes text into a file.
`TextReader`	`ReadLine()`	Reads one line of text.
`TextWriter`	`WriteLine("Hello!")`	Writes text with a new line.
`StringReader`	`ReadToEnd()`	Reads the entire string content.
`StringWriter`	`ToString()`	Returns the written content as a string.

📢 Events in System.IO (FileSystemWatcher)

Events help you track changes in folders and files.

Event Name	What It Does (Easy Explanation)
`Changed`	Triggers when a file is modified (like if someone edits it).
`Created`	Triggers when a new file or folder is added.
`Deleted`	Triggers when a file or folder is removed.
`Renamed`	Triggers when a file or folder is renamed.
`Error`	Triggers when an error happens (like if a file is suddenly locked).

🚨 Common Exceptions in File Handling (C#)

When working with files in C#, you might run into various exceptions. Below is a list of common file handling exceptions, along with simple explanations.

Exception Name	What It Means (Easy Explanation)
`IOException`	General file-related error (like reading a locked file).
`FileNotFoundException`	The file you’re trying to open doesn’t exist.
`DirectoryNotFoundException`	The folder path is incorrect or missing.
`UnauthorizedAccessException`	No permission to access the file or folder.
`PathTooLongException`	The file path or name is too long for the system to handle.
`NotSupportedException`	The file path format is incorrect or not supported.
`EndOfStreamException`	Trying to read beyond the end of the file.
`DriveNotFoundException`	The drive (like USB or external hard disk) is missing.
`FileLoadException`	The file is found but can’t be loaded (maybe corrupted).
`InvalidDataException`	The file contains invalid or unexpected data.
`SecurityException`	Security settings are preventing access to the file.
`ArgumentException`	The file path contains invalid characters.
`ObjectDisposedException`	You are trying to use a file that has already been closed.

🏆 Conclusion

Congratulations! 🎉 You’ve just explored the System.IO namespace in C# and got a glimpse of how it helps in file handling, directories, and streams. 🚀

We covered various classes, methods, properties, events, and exceptions that make it easier to work with files and data streams. These tools are crucial for building real-world applications like logging systems, data storage, and document management.

But don’t worry if it feels like a lot! 🤯 You’ll learn each of these in detail in the upcoming chapters, with hands-on examples to make things fun and easy. 😎

🔜 Next What?

Now that you understand System.IO, it’s time to get practical! In the next chapter, you’ll learn how to create files in C# file handling. 📂✍️

So, get ready to start working with actual files! See you there! 🚀

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