方法一： //最有含量的一种
int days = System.Threading.Thread.CurrentThread.CurrentUICulture.Calendar.GetDaysInMonth(DateTime.Now.Year ,DateTime.Now.Month);
方法二：//最奇怪的一种
DateTime dtNow = DateTime.Today;
int days = dtNow .AddDays(1 – dtNow .Day).AddMonths(1).AddDays(-1).Day;
方法三： //最常规的一种
DateTime dtNow = DateTime.Now;int days = DateTime.DaysInMonth(dtNow.Year ,dtNow.Month);
