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File system I/O operations are an important part of any programming language, and C# is no exception. Whether it is reading and writing files, operating directories, or processing file streams, C# provides a rich and powerful class library to implement these functions. This article will introduce file system I/O operations in C# in detail, and show how to efficiently process files and directories through code examples.

1. Read and write files

Writing to a file

In C#, you can useSystem.IOIn the namespaceFileClass to perform file writing operations.

Example:

using System;
using System.IO;
 
class Program
{
    static void Main()
    {
        string path = "example.txt";
        string content = "这是一个示例文本。";
 
        // 写入文件
        File.WriteAllText(path, content);
        Console.WriteLine("文件写入成功。");
    }
}

Reading a file

Similarly, we can also useFileClass to read file contents:

using System;
using System.IO;
 
class Program
{
    static void Main()
    {
        string path = "example.txt";
 
        if (File.Exists(path))
        {
            // 读取文件内容
            string content = File.ReadAllText(path);
            Console.WriteLine("文件内容：");
            Console.WriteLine(content);
        }
        else
        {
            Console.WriteLine("文件不存在。");
        }
    }
}

2. Using file streams

File streams provide a more flexible way to read and write files, especially when processing large files. File streams can read and write data byte by byte, thus avoiding excessive memory usage.

useFileStreamWriting to a file

using System;
using System.IO;
 
class Program
{
    static void Main()
    {
        string path = "filestream_example.txt";
        byte[] data = System.Text.Encoding.UTF8.GetBytes("通过FileStream写入的数据。");
 
        using (FileStream fs = new FileStream(path, FileMode.Create))
        {
            fs.Write(data, 0, data.Length);
            Console.WriteLine("数据已通过FileStream写入。");
        }
    }
}

useFileStreamReading a file

using System;
using System.IO;
 
class Program
{
    static void Main()
    {
        string path = "filestream_example.txt";
 
        using (FileStream fs = new FileStream(path, FileMode.Open))
        {
            byte[] data = new byte[fs.Length];
            fs.Read(data, 0, data.Length);
            string content = System.Text.Encoding.UTF8.GetString(data);
            Console.WriteLine("通过FileStream读取的内容：");
            Console.WriteLine(content);
        }
    }
}

3. Operation Directory

Create a directory

In C#, you can useDirectoryClass to create a directory:

using System;
using System.IO;
 
class Program
{
    static void Main()
    {
        string dirPath = "example_directory";
 
        if (!Directory.Exists(dirPath))
        {
            Directory.CreateDirectory(dirPath);
            Console.WriteLine("目录创建成功。");
        }
        else
        {
            Console.WriteLine("目录已存在。");
        }
    }
}

Deleting a Directory

can useDirectoryClass to delete a directory:

using System;
using System.IO;
 
class Program
{
    static void Main()
    {
        string dirPath = "example_directory";
 
        if (Directory.Exists(dirPath))
        {
            Directory.Delete(dirPath, true);
            Console.WriteLine("目录已删除。");
        }
        else
        {
            Console.WriteLine("目录不存在。");
        }
    }
}

4. Traversing files and directories

Get a list of files in a directory

can useDirectoryThe class gets a list of files in a specified directory:

using System;
using System.IO;
 
class Program
{
    static void Main()
    {
        string dirPath = "example_directory";
 
        if (Directory.Exists(dirPath))
        {
            string[] files = Directory.GetFiles(dirPath);
            Console.WriteLine("目录中的文件：");
            foreach (string file in files)
            {
                Console.WriteLine(file);
            }
        }
        else
        {
            Console.WriteLine("目录不存在。");
        }
    }
}

Recursive directory traversal

You can use a recursive algorithm to traverse all files in a directory and its subdirectories:

using System;
using System.IO;
 
class Program
{
    static void Main()
    {
        string dirPath = "example_directory";
 
        if (Directory.Exists(dirPath))
        {
            TraverseDirectory(dirPath);
        }
        else
        {
            Console.WriteLine("目录不存在。");
        }
    }
 
    static void TraverseDirectory(string dirPath)
    {
        string[] files = Directory.GetFiles(dirPath);
        string[] directories = Directory.GetDirectories(dirPath);
 
        foreach (string file in files)
        {
            Console.WriteLine("文件: " + file);
        }
 
        foreach (string directory in directories)
        {
            Console.WriteLine("目录: " + directory);
            TraverseDirectory(directory); // 递归遍历子目录
        }
    }
}

5. File attribute operations

In file system operations, reading and setting file attributes is a common requirement. C# providesFileInfoclass to implement this functionality.

Reading file attributes

using System;
using System.IO;
 
class Program
{
    static void Main()
    {
        string filePath = "example.txt";
 
        FileInfo fileInfo = new FileInfo(filePath);
 
        if (fileInfo.Exists)
        {
            Console.WriteLine("文件名: " + fileInfo.Name);
            Console.WriteLine("文件路径: " + fileInfo.FullName);
            Console.WriteLine("文件大小: " + fileInfo.Length);
            Console.WriteLine("创建时间: " + fileInfo.CreationTime);
            Console.WriteLine("最后访问时间: " + fileInfo.LastAccessTime);
            Console.WriteLine("最后修改时间: " + fileInfo.LastWriteTime);
        }
        else
        {
            Console.WriteLine("文件不存在。");
        }
    }
}

Setting file attributes

using System;
using System.IO;
 
class Program
{
    static void Main()
    {
        string filePath = "example.txt";
 
        FileInfo fileInfo = new FileInfo(filePath);
 
        if (fileInfo.Exists)
        {
            // 设置文件属性
            fileInfo.Attributes = FileAttributes.ReadOnly;
            Console.WriteLine("文件属性已设置为只读。");
 
            // 恢复文件属性
            fileInfo.Attributes = FileAttributes.Normal;
            Console.WriteLine("文件属性已恢复为正常。");
        }
        else
        {
            Console.WriteLine("文件不存在。");
        }
    }
}

6. Asynchronous file I/O operations

When processing large files or performing time-consuming file operations, using asynchronous methods can improve the responsiveness of the application. C# provides asynchronous methods to read and write files.

Writing files asynchronously

using System;
using System.IO;
using System.Threading.Tasks;
 
class Program
{
    static async Task Main()
    {
        string path = "async_example.txt";
        string content = "这是一个异步写入示例。";
 
        await File.WriteAllTextAsync(path, content);
        Console.WriteLine("文件异步写入成功。");
    }
}

Reading files asynchronously

using System;
using System.IO;
using System.Threading.Tasks;
 
class Program
{
    static async Task Main()
    {
        string path = "async_example.txt";
 
        if (File.Exists(path))
        {
            string content = await File.ReadAllTextAsync(path);
            Console.WriteLine("文件内容：");
            Console.WriteLine(content);
        }
        else
        {
            Console.WriteLine("文件不存在。");
        }
    }
}

7. File Monitoring

C# providesFileSystemWatcherClass for monitoring changes to files or directories in a specified directory. This is useful in applications that need to respond to file system changes.

useFileSystemWatcherWatching File Changes

using System;
using System.IO;
 
class Program
{
    static void Main()
    {
        string path = "example_directory";
 
        if (!Directory.Exists(path))
        {
            Directory.CreateDirectory(path);
        }
 
        FileSystemWatcher watcher = new FileSystemWatcher();
        watcher.Path = path;
        watcher.NotifyFilter = NotifyFilters.FileName | NotifyFilters.LastWrite | NotifyFilters.Size;
        watcher.Filter = "*.*";
 
        watcher.Changed += OnChanged;
        watcher.Created += OnChanged;
        watcher.Deleted += OnChanged;
        watcher.Renamed += OnRenamed;
 
        watcher.EnableRaisingEvents = true;
 
        Console.WriteLine("正在监视目录: " + path);
        Console.WriteLine("按任意键退出...");
        Console.ReadKey();
    }
 
    private static void OnChanged(object source, FileSystemEventArgs e)
    {
        Console.WriteLine($"文件: {e.FullPath} {e.ChangeType}");
    }
 
    private static void OnRenamed(object source, RenamedEventArgs e)
    {
        Console.WriteLine($"文件: {e.OldFullPath} 重命名为 {e.FullPath}");
    }
}

I hope this content is helpful to you, thank you for reading!