C# 为用户提供从文件系统中选择“.txt”的选项

我正在制作一个密码解密/加密机控制台应用程序

我想做的是为用户提供一个选项，使其能够从文件系统中选择一个.txt文件或在控制台窗口中键入。我知道如何读/写/保存“.txt”等，但我有点不确定实现它的最佳方法

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace Application
{


class Caesar
{
    static void Main(string[] args)
    {

       try{
        Console.WriteLine("Enter Key:");
        int k = Convert.ToInt32(Console.ReadLine());
        Console.WriteLine("What would you like to do?");
        Console.WriteLine("");
        Console.WriteLine("[E]   Encrypt");
        Console.WriteLine("[D]   Decrypt");
        string choice =Convert.ToString(Console.ReadLine()).ToUpper();

            // WOULD LIKE TO GIVE THE USER THE CHOICE BETWEEN TYPING OR  ADDING A .TXT FILE FROM THE FILSYSTEM
        switch (choice)
        {
            case "E": Console.Write("Enter Plain Text:");
                      string pt = Console.ReadLine();
                      caesar_cipher(k, pt);
                       break;

            case "D": Console.Write("Type CipherText :");
                       string ct = Console.ReadLine();
                      caesar_decipher(k, ct);
                      break;

            default: Console.WriteLine("You've entered an incorrect option!");
                       break;
        }
       }
       catch(Exception)
       {
           Console.WriteLine ("The value you entered is incorrect");
           Console.WriteLine ("Press any key to try again");
              Console.ReadKey();
        }


    }
    static void caesar_cipher(int key, string pt)
    {
        int size = pt.Length;
        char[] value = new char[size];
        char[] cipher = new char[size];
        for (int r = 0; r < size; r++)
        {
            value[r] = Convert.ToChar(pt.Substring(r, 1));
        }

        for (int re = 0; re < size; re++)
        {
            int count = 0;
            int a = Convert.ToInt32(value[re]);
            for (int y = 1; y <= key; y++)
            {
                if (count == 0)
                {
                    if (a == 90)
                    { a = 64; }
                    else if (a == 122)
                    { a = 96; }
                    cipher[re] = Convert.ToChar(a + y);
                    count++;
                }
                else
                {
                    int b = Convert.ToInt32(cipher[re]);
                    if (b == 90)
                    { b = 64; }
                    else if (b == 122)
                    { b = 96; }
                    cipher[re] = Convert.ToChar(b + 1);

                }
            }
        }
        string ciphertext = "";

        for (int p = 0; p < size; p++)
        {
            ciphertext = ciphertext + cipher[p].ToString();
        }
        Console.WriteLine("Cipher Text=");
        Console.WriteLine(ciphertext.ToUpper());
    }


    static void caesar_decipher(int key, string ct)
    {
        int size = ct.Length;
        char[] value = new char[size];
        char[] cipher = new char[size];
        for (int r = 0; r < size; r++)
        {
            cipher[r] = Convert.ToChar(ct.Substring(r, 1));
        }

        for (int re = 0; re < size; re++)
        {
            int count = 0;
            int a = Convert.ToInt32(cipher[re]);
            for (int y = 1; y <= key; y++)
            {
                if (count == 0)
                {
                    if (a == 65)
                    { a = 91; }
                    else if (a == 97)
                    { a = 123; }
                    value[re] = Convert.ToChar(a - y);
                    count++;
                }
                else
                {
                    int b = Convert.ToInt32(value[re]);
                    if (b == 65)
                    { b = 91; }
                    else if (b == 97)
                    { b = 123; }
                    value[re] = Convert.ToChar(b - 1);

                }
            }
        }
        string plaintext = "";

        for (int p = 0; p < size; p++)
        {
            plaintext = plaintext + value[p].ToString();
        }
        Console.WriteLine("Plain Text=");
        Console.WriteLine(plaintext.ToLower());
        Console.ReadKey();
    }
    }
}

---

您希望他们能够选择从文件系统中选择文件还是自己键入加密/纯文本字符串

或者您希望他们能够从文件系统中选择一个文件，或者自己键入文件路径

假设你的意思是后者，这是我解决你问题的办法

    [STAThread]
    static void Main(string[] args) {
        try {
            Console.Write("Enter key : ");
            int key = Convert.ToInt32(Console.ReadLine());
            Console.Write("Would you like to [E]ncrypt or [D]ecrypt? : ");
            string choice = Console.ReadLine().ToUpper();

            // Making the decision of writing the filepath or selecting the filepath.
            Console.Write("Would you like to [W]rite or [S]elect the file path? : ");
            string fileChoice = Console.ReadLine().ToUpper();

            string filePath = "";
            if(fileChoice == "W") {
                Console.WriteLine("Type the filepath the .txt file with your Cipher/Plain text");
                filePath = Console.ReadLine();
            }
            else {
                OpenFileDialog dial = new OpenFileDialog();
                dial.Filter = "Text files (*.txt)|*.txt";
                if (dial.ShowDialog() == DialogResult.OK)
                    filePath = dial.FileName;
            }

            string stringData;
            using (var reader = new StreamReader(filePath))
                stringData = reader.ReadToEnd();


            switch (choice) {
                case "E":
                    caesar_cipher(key, stringData);
                    break;

                case "D":
                    caesar_decipher(key, stringData);
                    break;

                default:
                    Console.WriteLine("You've entered an incorrect option!");
                    break;
            }

            Console.ReadLine();  // Added this to make sure you can read the end result.
        }
        catch (Exception) {
            Console.WriteLine("The value you entered is incorrect");
            Console.WriteLine("Press any key to try again");
            Console.ReadKey();
            Main(null); // This will call the main method allowing you to "try again".
        }
    }

---

一种可能的方法是允许用户通过将文件拖放到.exe上来启动程序，然后程序可以对文件内容进行加密或解密。如果程序是通过双击.exe启动的，那么它可以假定它将加密或解密来自控制台的用户输入

你可以这样做：

    public static void Main(string[] args)
    {
        // If args is not empty, then the user has dragged and dropped a file.
        bool inputFromFile = args.Length > 1;
        string input = string.Empty;
        if (inputFromFile)
        {
            // This contains the file path of the dragged and dropped file.
            string fileName = args[0];
            input = File.ReadAllText(fileName);
        }
        else
            input = Console.ReadLine();
    }

要测试这一点，如果您使用的是Visual Studio，则可以使用以下命令设置项目的命令行参数：