方法一: //最有含量的一種
int days = System.Threading.Thread.CurrentThread.CurrentUICulture.Calendar.GetDaysInMonth(DateTime.Now.Year ,DateTime.Now.Month);
方法二://最奇怪的一種
DateTime dtNow = DateTime.Today; int days = dtNow .AddDays(1 - dtNow .Day).AddMonths(1).AddDays(-1).Day;
方法三: //最常規的一種
DateTime dtNow = DateTime.Now; int days = DateTime.DaysInMonth(dtNow.Year ,dtNow.Month);