Calcolare il fuso orario rispetto alla UTC (Greenwich GMT)


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Calcolare il fuso orario rispetto alla UTC (Greenwich GMT)

Sfruttando qualche funzione dell'API è possibile calcolare, considerando anche l'ora legale, il fuso orario rispetto alla coordinata di tempo universale UTC (Greenwich GMT). Ecco quanto serve ^_^

' ritorna la data e l'ora di sistema
Private Declare Sub GetSystemTime Lib "kernel32" (lpSystemTime As SYSTEMTIME)

' ritorna la data e l'ora locale
Private Declare Sub GetLocalTime Lib "kernel32" (lpSystemTime As SYSTEMTIME)

Private Type SYSTEMTIME
    wYear As Integer
    wMonth As Integer
    wDayOfWeek As Integer
    wDay As Integer
    wHour As Integer
    wMinute As Integer
    wSecond As Integer
    wMilliseconds As Integer
End Type

Private Type TIME_ZONE_INFORMATION
   Bias As Long
   StandardName(0 To 63) As Byte
   StandardDate As SYSTEMTIME
   StandardBias As Long
   DaylightName(0 To 63) As Byte
   DaylightDate As SYSTEMTIME
   DaylightBias As Long
End Type

' ritorna un intero lungo che specifica il fuso orario rispetto a GMT
Public Function GetGMT() As Long

Dim SysTime As SYSTEMTIME
Dim LocTime As SYSTEMTIME
Dim SysDate As Date
Dim LocDate As Date
   
    ' ritorna l'ora corrente UTC (Greenwich)
    GetSystemTime SysTime
   
    ' ritorna l'ora locale
    GetLocalTime LocTime
   
    ' Data e Ora UTC (Greenwich GMT)
    SysDate = Format(SysTime.wDay & "-" & _
                    SysTime.wMonth & "-" & _
                    SysTime.wYear & " " & _
                    SysTime.wHour & ":" & _
                    SysTime.wMinute & ":" & _
                    SysTime.wSecond, "dd-mm-yyyy h:N:Ss")
                    
    ' Data e Ora Locale
    LocDate = Format(LocTime.wDay & "-" & _
                    LocTime.wMonth & "-" & _
                    LocTime.wYear & " " & _
                    LocTime.wHour & ":" & _
                    LocTime.wMinute & ":" & _
                    LocTime.wSecond, "dd-mm-yyyy h:N:Ss")
                    
    
    GetGMT = DateDiff("h", SysDate, LocDate)
	    
End Function

Esempio di utilizzo

Dim GMT As Long
Dim retVal As String
	
    GMT = GetGMT()    
    
    If GMT > 0 Then
        retVal = "GMT+" & GMT
		
    ElseIf GMT < 0 Then
        retVal = "GMT -" & GMT
		
    Else
        retVal = "GMT " & GMT
		
    End If
    
    MsgBox retVal, , "Fuso orario"