Eu fiz essa função aqui, você pode converte-la p/ c#:
Formatar data
Formatando uma data em diversos formatos:
Framework 1.1
Linguagem: VB.NET
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#Region "Method FormatDateTime()"
Public Function FormatDateTime(ByVal strDate As String, ByVal strFormat As String) As String
If strDate = "" Then Exit Function
If strFormat = "" Then Exit Function
Dim data As New System.DateTime(Year(strDate), Month(strDate), Day(strDate), Hour(strDate), Minute(strDate), Second(strDate))
Dim strReturn As String
Select Case strFormat
Case "DD/MM/YYYY"
strReturn = AddZero(data.Day) & "/" & AddZero(data.Month) & "/" & data.Year
Case "DD-MM-YYYY"
strReturn = AddZero(data.Day) & "-" & AddZero(data.Month) & "-" & data.Year
Case "DD.MM.YYYY"
strReturn = AddZero(data.Day) & "." & AddZero(data.Month) & "." & data.Year
Case "DD/MM/YYYY HH:MM:SS"
strReturn = AddZero(data.Day) & "/" & AddZero(data.Month) & "/" & data.Year
Case "DD-MM-YYYY HH:MM:SS"
strReturn = AddZero(data.Day) & "-" & AddZero(data.Month) & "-" & data.Year
Case "DD.MM.YYYY HH:MM:SS"
strReturn = AddZero(data.Day) & "." & AddZero(data.Month) & "." & data.Year
Case "HH:MM:SS"
strReturn = AddZero(data.Hour) & ":" & AddZero(data.Minute) & ":" & data.Second
End Select
Return strReturn
End Function
#End Region
#Region "Method AddZero()"
Function AddZero(ByVal str As String) As String
If str = "" Then Exit Function
If Len(str) = 1 Then str = "0" & str
Return str
End Function
#End Region
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Para chamar a função é simples:
FormatDateTime(now(),"DD/MM/YYYY HH:MM:SS")Forte abraço e até o próximo!