如何在集合中保存具有多个变量类型的对象以供以后调用

Question

我正在创建一个小程序，该程序接受用户输入(字符串和小数)，并在用户从菜单中选择"查看摘要"选项时将其打印回给用户。

菜单根据用户输入进行循环，账户名称/账户余额将在请求/输入后立即打印，但一旦选择选项3，我就无法保存和打印。尽管有任何输入，"查看摘要"每次都显示资产为0，债务为0。

Account类有一个字符串名称和十进制余额，我只希望它保存到用户完成为止。(没有数据库。现在只是想了解概念)

我的主要问题：
这是因为循环/列表是否应该在循环之外以捕获数据
字典是个更好的主意吗？我可以从一个空的集合开始吗？

static void Main(string[] args)
{
string menuChoice;
string response;
do
{
// Welcome/Menu screen
Console.WriteLine("nWelcome to your Net Worth Calculator.n n MENU:n 1. Add Assetn 2. Add Debtn 3. View Summary");
Console.WriteLine(" ");
Console.WriteLine("What would you like to do?nPlease make a selection: ");
menuChoice = Console.ReadLine();
Account asset = new Account();
var accountList = new List<Account>();
if (menuChoice == "1")
{
do
{ //D1
Console.WriteLine("nGreat! Let's add an account.");
Console.WriteLine("Account name:");
asset.name = Console.ReadLine();
Console.WriteLine("Your account name is: " + asset.name);
Console.WriteLine("nWhat is your current account balance with " + asset.name + "?");
Console.WriteLine("Balance:");
asset.balance = Decimal.Parse(Console.ReadLine());
accountList.Add(asset);
Console.WriteLine("Your balance with " + asset.name + " is currently $" + asset.balance + ".");
Console.WriteLine("nnWould you like to add another account? y/n");
response = Console.ReadLine();
} while (response != "n");
}
if (menuChoice == "3")
{
//D3
Console.WriteLine("Let's take a look at the accounts and balances that you've added so far:");
Console.WriteLine($"{asset.balance} is your asset, and {debt.balance} is your debt.");
decimal netWorth = asset.balance - debt.balance;
Console.WriteLine(netWorth);
Console.WriteLine($"{ asset.balance}");
Console.WriteLine("nnWould you like to add another account? y/n");
response = Console.ReadLine();
}

Answer 1

accountList必须在输入循环之外，这样无论选择哪个选项，您都可以访问它(读或写)。

类似这样的东西：

static void Main(string[] args)
{
string menuChoice;
string response;
var accountList = new List<Account>();
// Welcome/Menu screen
Console.WriteLine("nWelcome to your Net Worth Calculator.n n MENU:n 1. Add Assetn 2. Add Debtn 3. View Summary");
do
{
Console.WriteLine(" ");
Console.WriteLine("What would you like to do?nPlease make a selection: ");
menuChoice = Console.ReadLine();
if (menuChoice == "1")
{
do
{ //D1
Account asset = new Account();
Console.WriteLine("nGreat! Let's add an account.");
Console.WriteLine("Account name:");
asset.name = Console.ReadLine();
Console.WriteLine("Your account name is: " + asset.name);
Console.WriteLine("nWhat is your current account balance with " + asset.name + "?");
Console.WriteLine("Balance:");
asset.balance = Decimal.Parse(Console.ReadLine());
accountList.Add(asset);
Console.WriteLine("Your balance with " + asset.name + " is currently $" + asset.balance + ".");
Console.WriteLine("nnWould you like to add another account? y/n");
response = Console.ReadLine();
} while (response != "n");
}
if (menuChoice == "3")
{
//D3
Console.WriteLine("Let's take a look at the accounts and balances that you've added so far:");
Console.WriteLine($"{asset.balance} is your asset, and {debt.balance} is your debt.");
decimal netWorth = asset.balance - debt.balance;
Console.WriteLine(netWorth);
Console.WriteLine($"{ asset.balance}");
Console.WriteLine("nnWould you like to add another account? y/n");
response = Console.ReadLine();
}

Answer 2

do
{
// ...
Account asset = new Account();
var accountList = new List<Account>();
// ...
if (menuChoice == "3")
{
Console.WriteLine($"{asset.balance} is your asset, and {debt.balance} is your debt.");
}
} while (/* ... */);

在每个菜单循环上声明一个新的assset对象和accountList。当然，打印时assset.balance将为零，因为当您选择菜单选项#3时，它将始终是一个新对象。

您应该将列表移出菜单循环：

static void Main(string[] args)
{
string menuChoice;
string response;
var accountList = new List<Account>();
do { // ...

并且，在菜单选项#1:中创建Account的新实例

if (menuChoice == "1")
{
do
{ //D1
var asset = new Account();
// ... rest of your code
} while (response != "n");
}

---

至于计算资产和债务，你需要找到所有分别为正数或负数的账户：

var assets = accountList.Where(x => x.balance > 0).Sum(x => x.balance);
// assuming that you used negative value for debt
var debts = accountList.Where(x => x.balance < 0).Sum(x => x.balance);

理想情况下，您需要两种不同类型的Account来减少混乱的代码：

public abstract class Account
{
public string Name { get; set; }
public decimal Balance { get; set; }
}
public class Asset : Account { }
public class Debt : Account { }
// in option #3
accountList.OfType<Asset>().Sum(x => x.Balance);

Answer 3

一个问题与您所描述的完全一样，因为您在循环的每次迭代中都创建了accountList的新实例，它会丢失上次的信息。将其移出循环，如下所示。

如果你愿意的话，我想你可以用Dictionary<string, decimal>。优点是它不允许重复的键，并允许您按键访问值。如果你不需要这两样东西，那么List<T>就可以了。

还有一些其他问题，所以我对你的代码采取了一些自由，但我相信下面的内容符合你的要求：

void Main()
{
string menuChoice;
string response;
var accountList = new List<Account>();
var debtList = new List<Debt>();
do
{
response = "";
Console.WriteLine("nWelcome to your Net Worth Calculator.n n MENU:n 1. Add Assetn 2. Add Debtn 3. View Summaryn 4. Quit");
Console.WriteLine(" ");
Console.WriteLine("What would you like to do?nPlease make a selection: ");
menuChoice = Console.ReadLine();
if (menuChoice == "1")
{
do
{
Account asset = new Account();
Console.WriteLine("nGreat! Let's add an account.");
Console.WriteLine("Account name:");
asset.name = Console.ReadLine();
Console.WriteLine("Your account name is: " + asset.name);
Console.WriteLine("nWhat is your current account balance with " + asset.name + "?");
Console.WriteLine("Balance:");
asset.balance = Decimal.Parse(Console.ReadLine());
accountList.Add(asset);
Console.WriteLine("Your balance with " + asset.name + " is currently $" + asset.balance + ".");
Console.WriteLine("nnWould you like to add another account? y/n");
response = Console.ReadLine();
} while (response != "n");
}
if (menuChoice == "2")
{
do
{
Debt debt = new Debt();
Console.WriteLine("nGreat! Let's add a debt.");
Console.WriteLine("Debt name:");
debt.name = Console.ReadLine();
Console.WriteLine("Your debt name is: " + debt.name);
Console.WriteLine("nWhat is your current debt balance with " + debt.name + "?");
Console.WriteLine("Balance:");
debt.balance = Decimal.Parse(Console.ReadLine());
debtList.Add(debt);
Console.WriteLine("Your balance with " + debt.name + " is currently $" + debt.balance + ".");
Console.WriteLine("nnWould you like to add another debt? y/n");
response = Console.ReadLine();
} while (response != "n");
}
if (menuChoice == "3")
{
var totalAsset = accountList.Sum(x => x.balance);
var totalDebt = debtList.Sum(x => x.balance);
Console.WriteLine("Let's take a look at the accounts and balances that you've added so far:");
Console.WriteLine($"{totalAsset} is your asset, and {totalDebt} is your debt.");
decimal netWorth = totalAsset - totalDebt;
Console.WriteLine($"Net worth: {netWorth}");
Console.WriteLine("nnPress any key to return to the menu");
Console.ReadLine();
}
} while (menuChoice != "4");
}
public class Account
{
public string name {get;set;}
public decimal balance {get;set;}
}
public class Debt
{
public string name {get;set;}
public decimal balance {get;set;}
}

摘要：

• 将accountList移到循环之外，这样它就不会在下一次迭代中被擦除
• 添加了debtList来跟踪债务(假设你有这个但没有显示？)
• 为菜单选项2添加了部分(再次假设您刚刚错过了它？)
• 更改了菜单选项3中的逻辑以正确显示总计
• 添加了在选择菜单选项4(退出)时退出的逻辑

根据共同的账户/债务份额，您可能只能有一个类别，而不是两个类别。