C# 시작하기 - System.IO

The System.IO namespace in C# provides types that allow synchronous and asynchronous reading and writing on data streams and files. It includes classes for managing directories, files, and streams, among other things.

Key Classes and Their Purposes:

1. File:
   • Provides static methods for file operations such as creation, deletion, copying, and moving.
   • Example: File.Create(), File.Delete(), File.ReadAllText().
2. Directory:
   • Provides static methods for directory operations such as creation, deletion, moving, and enumerating files and directories.
   • Example: Directory.CreateDirectory(), Directory.Delete(), Directory.GetFiles().
3. FileInfo:
   • Provides instance methods for creating, copying, deleting, moving, and opening files, and aids in the creation of FileStream objects.
   • Example: FileInfo.Create(), FileInfo.Delete(), FileInfo.CopyTo().
4. DirectoryInfo:
   • Provides instance methods for creating, moving, and enumerating through directories and subdirectories.
   • Example: DirectoryInfo.Create(), DirectoryInfo.Delete(), DirectoryInfo.GetFiles().
5. FileStream:
   • Provides a stream for file operations, enabling reading and writing on files.
   • Example: FileStream.Read(), FileStream.Write(), FileStream.Seek().
6. StreamReader:
   • Implements a TextReader that reads characters from a byte stream in a particular encoding.
   • Example: StreamReader.ReadLine(), StreamReader.ReadToEnd().
7. StreamWriter:
   • Implements a TextWriter that writes characters to a stream in a particular encoding.
   • Example: StreamWriter.WriteLine(), StreamWriter.Write().
8. Path:
   • Provides methods for processing directory strings in a cross-platform manner.
   • Example: Path.Combine(), Path.GetExtension(), Path.GetFileName().

Example: Reading and Writing to a File

Here's a practical example that demonstrates reading from and writing to a file using StreamWriter and StreamReader:

using System;
using System.IO;

class Program
{
    static void Main()
    {
        string filePath = "example.txt";

        // Write to the file
        using (StreamWriter writer = new StreamWriter(filePath))
        {
            writer.WriteLine("Hello, System.IO!");
            writer.WriteLine("This is a test file.");
        }

        // Read from the file
        using (StreamReader reader = new StreamReader(filePath))
        {
            string content;
            while ((content = reader.ReadLine()) != null)
            {
                Console.WriteLine(content);
            }
        }

        // Delete the file
        File.Delete(filePath);
    }
}

Explanation:

1. StreamWriter: Writes text to the file example.txt.
2. StreamReader: Reads the content from the file line by line.
3. File.Delete: Deletes the file after reading its content.