c# - 计算到下一个指定日期的剩余天数

Question

如果DAY(第 2、25 日等)已知，在这种情况下您需要计算下一个“账单日期”，您如何计算距离下一次账单支付还有多少天？

解释:

Tom's bill gets generated on the 4th of every month

计算下一张账单前剩余天数的最佳方法/逻辑是什么？例如，如果今天是本月 28 日，则结果将是 还剩 6 天

我们所知道的:

Bill Generation Date is known

Today's Date is known

到目前为止我做了什么:

int billingDay = 4; //The day the bill gets generated every month
DateTime today = DateTime.Today; //Today's date

我将如何继续计算下一个账单日期？

P.S:对不起，如果这听起来很蹩脚，我只是无法理解它:)

Answer 1

我认为这行得通:

private int GetNumDaysToNextBillingDate(int billingDayOfMonth)
{
    DateTime today = DateTime.Today;

    if (today.Day <= billingDayOfMonth)
    {
        return (new DateTime(today.Year, today.Month, billingDayOfMonth) - today).Days;
    }
    else
    {
        var oneMonthFromToday = today.AddMonths(1);

        var billingDateNextMonth = 
            new DateTime(oneMonthFromToday.Year, 
            oneMonthFromToday.Month, billingDayOfMonth);

        return (billingDateNextMonth - today).Days;
    }
}