如何确定给定日期是否是该月的第 N 个工作日? [英] How do I determine if a given date is the Nth weekday of the month?

问题描述

这是我想要做的:给定日期、星期几和整数n，判断日期是否是该月的第n天.

Here is what I am trying to do: Given a date, a day of the week, and an integer n, determine whether the date is the nth day of the month.

例如:

• 1/1/2009,Monday,2 的输入将是错误的，因为 1/1/2009 不是第二个星期一

• input of 1/1/2009,Monday,2 would be false because 1/1/2009 is not the second Monday

输入2008 年 11 月 13 日，星期四，2将返回 true，因为这是第二个星期四

input of 11/13/2008,Thursday,2 would return true because it is the second Thursday

如何改进这个实现?

private bool NthDayOfMonth(DateTime date, DayOfWeek dow, int n)
{
    int d = date.Day;
    return date.DayOfWeek == dow && (d/ 7 == n || (d/ 7 == (n - 1) && d % 7 > 0));
}

推荐答案

你可以改变一周的检查，这样函数就会变成:

You could change the check of the week so the function would read:

private bool NthDayOfMonth(DateTime date, DayOfWeek dow, int n){
  int d = date.Day;
  return date.DayOfWeek == dow && (d-1)/7 == (n-1);
}

除此之外，它看起来还不错且高效.

Other than that, it looks pretty good and efficient.

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