Local时间向GMT时间的转化（ASP）

'====================================================================
'機能 : ローカル日付をＧＭＴ日付に変換する。
'引数 :　　
'  ローカル日付
'返却値 : ＧＭＴ日付
'====================================================================
Function gfdtLocal2GMT(ByVal LocalDate)

 If SG_blnErrorResumeNext Then
  On Error Resume Next
 End If

 Dim intTime
 Dim intMinute
 Dim dtTempDate
 Dim dtOutDate

 If Left(SG_strTimeZone, 3) <> "GMT" Then
  gfdtLocal2GMT = LocalDate
  Exit Function
 Else
  Select Case Mid(SG_strTimeZone, 4, 1)
   Case "+"
    intTime = Mid(SG_strTimeZone, 5, 2)
    intMinute = Mid(SG_strTimeZone, 8, 2)
    If 0 <= intTime And intTime < 24 Then
     If 0 <= intMinute And intMinute < 60 Then
      dtTempDate = DateAdd("h", -intTime, LocalDate)
      dtOutDate = DateAdd("n", -intMinute, dtTempDate)

     Else
      gfdtLocal2GMT = LocalDate
      Exit Function
     End If
    Else
     gfdtLocal2GMT = LocalDate
     Exit Function
    End If
   Case "-"
    intTime = Mid(SG_strTimeZone, 5, 2)
    intMinute = Mid(SG_strTimeZone, 8, 2)
    If 0 <= intTime And intTime < 24 Then
     If 0 <= intMinute And intMinute < 60 Then
      dtTempDate = DateAdd("h", intTime, LocalDate)
      dtOutDate = DateAdd("n", intMinute, dtTempDate)
     Else
      gfdtLocal2GMT = LocalDate
      Exit Function
     End If
    Else
     gfdtLocal2GMT = LocalDate
     Exit Function
    End If
   Case Else
    gfdtLocal2GMT = LocalDate
    Exit Function
   End Select
 End If
 gfdtLocal2GMT = cdate(dtOutDate)

End Function