DateTime dtStartTime = new DateTime(2017, 10, 9, 8, 30, 52);
DateTime dtEndTime = new DateTime(2017, 10, 12, 8, 30, 52);
DateTime dtloopStartTime = new DateTime(2017, 10, 12, 8, 0, 0);
DateTime dtLoopEndTime = new DateTime(2017, 10, 12, 23, 0, 0);
DateTime iStartTime = dtStartTime.Date;
DateTime iEndTime = dtEndTime.Date;
int loopStart = dtloopStartTime.Hour;
int loopEnd = dtLoopEndTime.Hour;
DateTime createTime = DateTime.Now;
DateTime modifiedon = DateTime.Now;
if (iStartTime < createTime.Date && iEndTime < createTime && loopStart < createTime.Hour && createTime.Hour < loopEnd)
{
Console.WriteLine("Do tasks");
}