编辑代码

using System;

class Program{
    static void Main(straing[] args){
 Console.Write("请输入用户名: ");
 string username = Console.ReadLine();

  if(username == "admin"){
      Console.Write("请输入密码: ");
      string password = Console.ReadLine();

      if(password == "888888"){
        Console.WriteLine("登录成功");
      }
      else{
          Console.WriteLine("密码错误");
      }
  }else{
      Console.WriteLine("用户名不存在");
  }
Console.ReadKey()
}
}