C# - 更换背包中的元素

Question

我正在尝试创建一个简单的背包程序。这是学校的作业，我快完成了，只是我无法用新的东西替换我背包里的东西。

我猜测为什么它可能不起作用是因为我无法替换 item 因为它在全局范围内，但我不知道如何修复它。这是代码:

static void Main(string[] args)
    {
        bool isRunning = true;
        while (isRunning)
        {
            Console.WriteLine("\n\tWelcome to the backpack!");
            Console.WriteLine("\t[1]Add an item");
            Console.WriteLine("\t[2]Show contents");
            Console.WriteLine("\t[3]Clear contents");
            Console.WriteLine("\t[4]Exit");
            Console.Write("\tChoose: ");

            int menyVal = Convert.ToInt32(Console.ReadLine());

            string item;
            item = "Empty space";


            switch (menyVal)
            {
                case 1:
                    Console.WriteLine("\n\tContents of backpack:");
                    Console.WriteLine("\n\t" + item);
                    Console.WriteLine("\n\tWhat do you want to replace " + item + " with?");
                    item = item.Replace(item, Console.ReadLine()); 
                    Console.WriteLine("\n\tYou have packed " + item + " in your backpack");
                    break;
                case 2:
                    Console.WriteLine("\n\tContents of backpack:");
                    Console.WriteLine("\n\t" + item);
                    Console.WriteLine("\n\tPress any key...");
                    Console.ReadKey();
                    break;
                case 3:
                    item = "Tom plats";
                    Console.WriteLine("\n\tYou have emptied the backpack!");
                    break;
                case 4:
                    isRunning = false;
                    break;
                default:
                    Console.WriteLine("Incorrect input!");
                    break;
            }
        }
    }

关于如何解决这个问题的任何想法？非常感谢提示!谢谢!

Answer 1

移动赋值

string item;
item = "Empty space";

在 while 循环之前。

现在，每次循环都会覆盖项目值。

下面是整个代码在更改后的样子:

static void Main(string[] args)
    {
        bool isRunning = true;
        string item = "Empty space";

        while (isRunning)
        {
            Console.WriteLine("\n\tWelcome to the backpack!");
            Console.WriteLine("\t[1]Add an item");
            Console.WriteLine("\t[2]Show contents");
            Console.WriteLine("\t[3]Clear contents");
            Console.WriteLine("\t[4]Exit");
            Console.Write("\tChoose: ");

            int menyVal = Convert.ToInt32(Console.ReadLine());

            switch (menyVal)
            {
                case 1:
                    Console.WriteLine("\n\tContents of backpack:");
                    Console.WriteLine("\n\t" + item);
                    Console.WriteLine("\n\tWhat do you want to replace " + item + " with?");
                    item = Console.ReadLine());
                    Console.WriteLine("\n\tYou have packed " + item + " in your backpack");
                    break;
                case 2:
                    Console.WriteLine("\n\tContents of backpack:");
                    Console.WriteLine("\n\t" + item);
                    Console.WriteLine("\n\tPress any key...");
                    Console.ReadKey();
                    break;
                case 3:
                    item = "Tom plats";
                    Console.WriteLine("\n\tYou have emptied the backpack!");
                    break;
                case 4:
                    isRunning = false;
                    break;
                default:
                    Console.WriteLine("Incorrect input!");
                    break;
            }
        }
    }