ASP.NET C#如何获取当月或上个月的第一天和最后一天

////获取当月第一天与最后一天//DateTime DateNow = DateTime.Now;//DateTime DateBegin = new DateTime(DateNow.Year, DateNow.Month, 1);//DateTime DateEnd = DateBegin.AddMonths(1).AddDays(-1);//获取上个月第一天与最后一天DateTime DateNow = DateTime.Now.AddMonths(-1);DateTime DateBegin = new DateTime(DateNow.Year, DateNow.Month, 1);DateTime DateEnd = DateBegin.AddMonths(1).AddDays(-1);