convert local time to utc

Question

I have following function to get utc time. dtuniversal I pass to stroed proc of sql server data type time. it works fine upto values 6 PM eastern ( which is 23 utc) it fails on 7 PM eastern ( which is 24 utc) I get error "Invalid value for this metadata".

Private Function GetUTCTime(ByVal time As TimeSpan) As TimeSpan

  Dim dt As New DateTime(time.Ticks)
  dt = dt.ToUniversalTime()
  Dim dtUniversal As New TimeSpan(dt.Ticks)
  Return dtUniversal

 End Function

Answer 1

The following test code suggests that the variable time(aTimeSpan) should be looked at.

Private Sub Button1_Click(ByVal sender As System.Object, _
                          ByVal e As System.EventArgs) Handles Button1.Click


    Dim ts As New TimeSpan(DateTime.Now.Ticks) 'create a test timespan
    'Dim ts As New TimeSpan(0,0,0) 'create a test timespan
    Dim oneHr As New TimeSpan(1, 0, 0) 'one hour increments

    For x As Integer = 0 To 24 '25 calls to GetUTCTime
        Debug.WriteLine("     '" & GetUTCTime(ts).ToString)
        ts = ts.Add(oneHr) 'add one hour
    Next
End Sub

Private Function GetUTCTime(ByVal aTimeSpan As TimeSpan) As TimeSpan
    'i don't like to use variable names that are keywords
    Dim dt As New DateTime(aTimeSpan.Ticks)
    dt = dt.ToUniversalTime()
    Dim dtUniversal As New TimeSpan(dt.Ticks)
    Return dtUniversal

End Function

'debug output
'733980.22:23:08.8112022
'733980.23:23:08.8112022
'733981.00:23:08.8112022
'733981.01:23:08.8112022
'733981.02:23:08.8112022
'733981.03:23:08.8112022
'733981.04:23:08.8112022
'733981.05:23:08.8112022
'733981.06:23:08.8112022
'733981.07:23:08.8112022
'733981.08:23:08.8112022
'733981.09:23:08.8112022
'733981.10:23:08.8112022
'733981.11:23:08.8112022
'733981.12:23:08.8112022
'733981.13:23:08.8112022
'733981.14:23:08.8112022
'733981.15:23:08.8112022
'733981.16:23:08.8112022
'733981.17:23:08.8112022
'733981.18:23:08.8112022
'733981.19:23:08.8112022
'733981.20:23:08.8112022
'733981.21:23:08.8112022
'733981.22:23:08.8112022

If you are just changing from local to UTC and back:

'a test date in local time
Dim d As DateTime = DateTime.Now
'convert local to UTC
Dim u As DateTime = d.ToUniversalTime
'convert UTC to local
Dim nd As DateTime = u.ToLocalTime

Either you are making this harder than it is, or I am missing something

    Dim d As DateTime = DateTime.Parse("10:00:00") 'this is local central daylight
    Dim u As DateTime = d.ToUniversalTime 'this is universal
    d = u.ToLocalTime 'double check