Question

我正在做一个项目，我必须计算年初至今每日复利的交易。目前我只是没有兴趣获得当前的余额。我相信我的问题是关于foreach循环，但我不确定我在哪里犯了错误。它正在经历这些日子，但是没有任何兴趣被应用或者运行总体没有正常进行。

                public IEnumerable<DateTime> EachDay(DateTime from, DateTime thru)
    {
        for (var day = from.Date; day.Date <= thru.Date; day = day.AddDays(1))
            yield return day;
    }

    public decimal PrincipalplusInterest()
    {
        DateTime startDate = new DateTime( DateTime.Now.Year, 1, 1);
        DateTime endDate = startDate.AddYears(1);
        int compoundingTimes = 12;

        TimeSpan duration = endDate - startDate;
        var numberOfDaysInYear = duration.Days;

        decimal runningTotal = 0;
        double interestRate = InterestRate;

        foreach (DateTime day in EachDay(startDate, endDate))
        {
            decimal sumOfAnyTransactionToday = Transactions.Where(x => x.TransactionDate == day).Sum(x => x.Amount);

            runningTotal = runningTotal + sumOfAnyTransactionToday;

            double timePeriod = 1 / numberOfDaysInYear;
            double rate = interestRate / compoundingTimes;
            double total = System.Convert.ToDouble(runningTotal);

            double principalAndInterest = total * Math.Pow((1 + rate), (compoundingTimes * timePeriod));
            runningTotal = System.Convert.ToDecimal(principalAndInterest);

        }
        return runningTotal;
    }


    [DisplayName("Year to Date Interest")]
    public decimal YrToDateInterest()
    {
        decimal interest = PrincipalplusInterest() - CurrentBalanceCalculation();
        return interest;
    }

Answer 1

你在这里做整数运算：

double timePeriod = 1 / numberOfDaysInYear;

numberOfDaysInYear是一个int，因此将1除以此值将始终返回0.

通过使其中一个值浮点来计算浮点数：

double timePeriod = 1.0 / numberOfDaysInYear;

可能是最简单的解决方案。

此外，如果您的交易包含时间组件，那么此语句将始终返回零，除非您恰好在午夜发生交易。

Transactions.Where(x => x.TransactionDate == day).Sum(x => x.Amount);

要获取您需要的日期，请获取Date对象的DateTime组件：

Transactions.Where(x => x.TransactionDate.Date == day).Sum(x => x.Amount);

每日复利兴趣圈

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