VB.net - Function หาวันแรกและวันสุดท้ายของเดือน

Private Function GetFirstDayOfMonth(ByVal _ 


        dtDate As DateTime) As DateTime  


 Dim dtFrom As DateTime = dtDate 

 dtFrom = dtFrom.AddDays(-(dtFrom.Day - 1)) 

 Return dtFrom  

End Function 


Private Function GetLastDayOfMonth(ByVal _ 


        dtDate As DateTime) As DateTime  


 Dim dtTo As New DateTime(dtDate.Year, _


       dtDate.Month, 1)  

 dtTo = dtTo.AddMonths(1)  

 dtTo = dtTo.AddDays(-(dtTo.Day))   

 Return dtTo  

End Function