Imports System

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Public Class Program

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    Public Shared Sub Main()

        Dim dt1 = DateTime.Parse("2011-08-11 4:59")

        Dim dt2 = DateTime.Parse("2011-08-11 5:00")

        Dim dt3 = DateTime.Parse("2011-08-11 5:01")

        Console.WriteLine(dt1)

        Console.WriteLine(dt2)

        Console.WriteLine(dt3)

        Dim r1 = RoundUp(dt1, TimeSpan.FromMinutes(15))

        'Dim r2 = RoundUp(dt2, TimeSpan.FromMinutes(15))

        'Dim r3 = RoundUp(dt3, TimeSpan.FromMinutes(15))

        Console.WriteLine("--------------------")

        Console.WriteLine(r1)

    'Console.WriteLine(r2)

    'Console.WriteLine(r3)

    End Sub

​

    Private Shared Function RoundUp(ByVal dt As DateTime, ByVal ds As TimeSpan) As DateTime

        dim dtTicks as Int64 = dt.Ticks

        dim dsTicks as Int64 = ds.Ticks

        dim d1 as Int64 =(dtTicks + dsTicks - 1)

        dim d2 as Int64 =(d1 / dsTicks)

        dim d3 as Int64 =(d2 * dsTicks)

        Console.WriteLine("dt=" + dtTicks.ToString())

        Console.WriteLine("ds=" + dsTicks.ToString())

        Console.WriteLine("d1=" + d1.ToString())

        Console.WriteLine("d2=" + d2.ToString())    '70498485 not 70498484

        Console.WriteLine("d3=" + d3.ToString())

        return new DateTime(d3, dt.Kind)

    End Function

End Class

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