列出本年度所有星期天的日期

这题与《列出本月所有星期天的日期》有点相似，稍微变动一下，即可完成。

 public IEnumerable<DateTime> AllSundaysInYear(int year)
    {
        System.Globalization.CultureInfo ci = new System.Globalization.CultureInfo("en-US");
        for (int m = 1; m <= 12; m++)
        {
            int days = ci.Calendar.GetDaysInMonth(year, m);

            for (int i = 1; i <= days; i++)
            {
                if (new DateTime(year, m, i).DayOfWeek == DayOfWeek.Sunday)
                    yield return new DateTime(year, m, i);
            }
        }
    }