如何获取特定月份/年中特定日期的总数？

Question

假设我想知道2014年2月的星期一数量.

我知道这将使用DateTime类,但是希望看到一些编码示例.

Answer 1

static int NumberOfParticularDaysInMonth(int year, int month, DayOfWeek dayOfWeek)
{
    DateTime startDate = new DateTime(year, month, 1);
    int totalDays = startDate.AddMonths(1).Subtract(startDate).Days;

    int answer = Enumerable.Range(1, totalDays)
        .Select(item => new DateTime(year, month, item))
        .Where(date => date.DayOfWeek == dayOfWeek)
        .Count();

    return answer;
}

...

int numberOfThursdays = NumberOfParticularDaysInMonth(2010, 9, DayOfWeek.Thursday);