無差別に技術をついばむ鳥

Imports System
Imports System.Diagnostics

Module Module1

    Sub Main()
        Dim watch As Stopwatch = New Stopwatch()
        Const max As Integer = 1000000
        Dim result As Double = 0

        '値引渡し
        watch.Start()
        For i As Integer = 0 To max
            result = Calculate(i)
            'resultを使って何かの計算をする
        Next
        watch.Stop()
        Console.WriteLine( _
            "値引渡し時の実行時間は{0}ミリ秒です。", _
            watch.ElapsedMilliseconds)

        '参照引渡し
        watch.Reset()
        watch.Start()
        For i As Double = 0 To max
            result = i
            RefCalculate(result)
            'resultを使って何かの計算をする
        Next
        watch.Stop()
        Console.WriteLine( _
            "参照引渡し時の実行時間は{0}ミリ秒です。", _
            watch.ElapsedMilliseconds)
    End Sub

    Private Function Calculate(ByVal value As Integer) As Double
        Return value * DateTime.Now.Millisecond
    End Function

    Private Sub RefCalculate(ByRef value As Double)
        value *= DateTime.Now.Millisecond
    End Sub
End Module