创建一个C#控制台应用实现用户的注册与登录

好的，以下是一个 C# 控制台应用的示例代码，实现用户的注册与登录功能：

using System;
using System.IO;

namespace UserRegistrationLogin
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Welcome to User Registration and Login System!\n");

            while (true)
            {
                Console.WriteLine("1. Register");
                Console.WriteLine("2. Login");
                Console.WriteLine("3. Exit");
                Console.Write("\nPlease select an option: ");
                string option = Console.ReadLine();

                switch (option)
                {
                    case "1":
                        Register();
                        break;
                    case "2":
                        Login();
                        break;
                    case "3":
                        Console.WriteLine("\nThank you for using our system! Goodbye!");
                        return;
                    default:
                        Console.WriteLine("\nInvalid option! Please select again.\n");
                        break;
                }
            }
        }

        static void Register()
        {
            Console.WriteLine("\nUser Registration\n");

            Console.Write("Enter username: ");
            string username = Console.ReadLine();

            Console.Write("Enter password: ");
            string password = Console.ReadLine();

            if (IsUserExists(username))
            {
                Console.WriteLine("\nThis username already exists! Please try again.\n");
            }
            else
            {
                using (StreamWriter writer = new StreamWriter("users.txt", true))
                {
                    writer.WriteLine(username + "," + password);
                }

                Console.WriteLine("\nRegistration successful!\n");
            }
        }

        static void Login()
        {
            Console.WriteLine("\nUser Login\n");

            Console.Write("Enter username: ");
            string username = Console.ReadLine();

            Console.Write("Enter password: ");
            string password = Console.ReadLine();

            if (IsUserExists(username))
            {
                string[] user = GetUser(username);

                if (user[1] == password)
                {
                    Console.WriteLine("\nLogin successful!\n");
                }
                else
                {
                    Console.WriteLine("\nIncorrect password! Please try again.\n");
                }
            }
            else
            {
                Console.WriteLine("\nThis username does not exist! Please register first.\n");
            }
        }

        static bool IsUserExists(string username)
        {
            using (StreamReader reader = new StreamReader("users.txt"))
            {
                string line;
                while ((line = reader.ReadLine()) != null)
                {
                    string[] user = line.Split(',');

                    if (user[0] == username)
                    {
                        return true;
                    }
                }
            }

            return false;
        }

        static string[] GetUser(string username)
        {
            using (StreamReader reader = new StreamReader("users.txt"))
            {
                string line;
                while ((line = reader.ReadLine()) != null)
                {
                    string[] user = line.Split(',');

                    if (user[0] == username)
                    {
                        return user;
                    }
                }
            }

            return null;
        }
    }
}

这个示例代码中，用户的信息存储在 users.txt 文件中，每行一个用户的用户名和密码，用逗号隔开。用户可以选择注册或登录，根据用户输入的选项进行相应的操作。在用户注册时，将用户名和密码写入文件中；在用户登录时，读取文件中的用户信息，逐行比对用户名和密码是否匹配。