根据彼此的属性用对象填充列表答案

【问题标题】：Fill a list with objects depending on eachothers attributes根据彼此的属性用对象填充列表
【发布时间】：2014-03-05 08:44:51
【问题描述】：

我有一个列表，我想使用列表中创建的最新对象来计算下一个对象属性。我不确定如何编写循环来做到这一点。你能帮我解决这个问题吗？

public ActionResult ShowDetail(DateTime startdate, double PresentValue, double InterestRate, double FutureValue, int PaymentPeriods)
    {
        List<Calculation> cList = new List<Calculation>();
        Calculation calc = new Calculation();
        calc.Date = startdate.ToShortDateString();
        calc.InvoiceAmount = 2000;
        calc.InterestRate = InterestRate;
        calc.InterestAmount = (PresentValue * InterestRate / 360 * 30);
        calc.Amortization = (2000 - (PresentValue * InterestRate / 360 * 30));
        calc.PresentValue = PresentValue;
        cList.Add(calc);
        for (int i = 0; i < PaymentPeriods; i++)
        {
            cList.Add(new Calculation()
                {
                    var calcBefore = cList.GetLastObject //Some how I want to take the object before the one i want to create
                    cList.Add(new Calculation()
                    {
                        Date = calcBefore.Date.Add(1).Month() //something like this
                        InvoiceAmount = calcBefore.InvoiceAmount
                        InterestRate = calcBefore.InterestRate
                        InterestAmount = (calcBefore.PresentValue * InterestRate / 360 * 30) //I want to take the presentvalue from the object before in the List and use that to calculate the the next InterestAmount
                        //And so on
                    }
                });
        }

        return PartialView("ShowDetail", cList);
    }

计算：

public partial class Calculation
{
   public string Date { get; set; }
   public double InvoiceAmount { get; set; }
   public double InterestRate { get; set; }
   public double InterestAmount { get; set; }
   public double Amortization { get; set; }
   public double PresentValue { get; set; }
}

【问题讨论】：

“我不确定如何编写循环来做到这一点。” ?将编辑文本，以便您更轻松地查看它

标签： c# list loops

【解决方案1】：

您可以使用列表的索引来访问最后插入的：

var calcBefore = cList[cList.Count - 1];

另一种相同的方式：Enumerable.Last:

var calcBefore = cList.Last();

由于您在循环之前添加了一个，因此列表不为空，这是安全的。

这是完整的循环：

for (int i = 0; i < PaymentPeriods; i++)
{
    calc = new Calculation();
    Calculation calcBefore = cList[cList.Count - 1];
    calc.Date = DateTime.Parse(calcBefore.Date).AddMonths(1).ToString();
    calc.InvoiceAmount = calcBefore.InvoiceAmount;
    calc.InterestRate = calcBefore.InterestRate;
    calc.InterestAmount = (calcBefore.PresentValue * InterestRate / 360 * 30);//I want to take the presentvalue from the object before in the List and use that to calculate the the next InterestAmount
    cList.Add(calc);
}

根据Date，我假设你想增加一个月，使用DateTime.AddMonths：

Date = DateTime.Parse(calcBefore.Date).AddMonths(1).ToString();

但是，我根本不会将String 用于DateTime。

【讨论】：

字符串只是用于测试，但现在将更改它:) 也将测试您的代码

【解决方案2】：

不要认为你会使用循环，

您所要做的就是让构造函数将 Calculation 对象作为参数。

然后你会做类似的事情

public partial class Calculation
{
   public string Date { get; set; }
   public double InvoiceAmount { get; set; }
   public double InterestRate { get; set; }
   public double InterestAmount { get; set; }
   public double Amortization { get; set; }
   public double PresentValue { get; set; }

public   Calculation (Calculation as calculation(
   {
    ..  set you prop
   }
}

那么当你调用一个新对象时，你传入当前列表中的最后一个对象

var newObj = new Calculation(cList[cList.Length -1]);

【讨论】：