C# 獲取從1月至12月的月初時間和月末時間

public IActionResult GetMonthData()
{
       var dataList = new List<object>();

       var currentMonth = DateTime.Now.Month;                       //獲取當月
       var currentDay = DateTime.Now.Day;                              //...........天
       var currentHour = DateTime.Now.Hour;                           //...........時
       var currentMinute = DateTime.Now.Minute;                     //...........分
       var currentMillisecond = DateTime.Now.Millisecond;       //............秒

for (int i = 1; i <= 12; i++)
{
      var monthStart = DateTime.Now.AddMonths(i - currentMonth).AddDays(1-currentDay).AddHours(-currentHour)
                       .AddMinutes(-currentMinute).AddMilliseconds(-currentMillisecond);

       var monthEnd = DateTime.Now.AddMonths(i - currentMonth+1).AddDays(1 - currentDay-1).AddHours(-currentHour)
                       .AddMinutes(-currentMinute).AddMilliseconds(-currentMillisecond);

       dataList.Add(new monthStart=monthStart,monthEnd = monthEnd });
}

       return Json(dataList); ;
}