获取某个月的第一天和最后一天

网上有很多种实现方式，我比较倾向于下面这种方式。我为了熟悉下委托的用法，用了下面的写法，高手们见笑了啊！其实是完全可以不用委托。
protected delegate DateTime DayofMonth(int year, int month);

DateTime dayNow = DateTime.Now;

protected void Page_Load(object sender, EventArgs e)

{

if (!IsPostBack)

{

DayofMonth GetFirstDay = new DayofMonth(FirstDayOfMonth);

firstDay.Value = GetFirstDay(dayNow.Year, dayNow.Month);

DayofMonth GetLastDay = new DayofMonth(LastDayOfMonth);

lastDay.Value = GetLastDay(dayNow.Year, dayNow.Month);

}

}

protected DateTime FirstDayOfMonth(int year, int month)

{

string firstDay = year.ToString() + "-" + month.ToString() + "-" + "1";

return Convert.ToDateTime(firstDay);

}

protected DateTime LastDayOfMonth(int year, int month)

{

string lastDay = year.ToString() + "-" + month.ToString() + "-" + DateTime.DaysInMonth(year, month);

return Convert.ToDateTime(lastDay);

}

上面是源码直接黏贴过来了。firstDay这个控件是我自定义的用户控件，将在另外一篇 日历控件 中介绍。