问测量代码执行所用的时间

EN

Function primeNumber()
    Dim Start_Time As DateTime
    Dim Stop_Time As DateTime
    Dim Elapsed_Time As TimeSpan
    Start_Time = Now
    Dim Check As Integer
    Check = 1
    Dim num As Long
    Console.WriteLine("Please enter the number you would like to determine if it is a Prime Number or not")
    num = Long.Parse(Console.ReadLine())
    If (num > 0) Then
        For i = 2 To (num - 1)
            If num Mod i = 0 Then
                Check = 0
                Exit For
            End If
        Next
        If Check = 0 Then
            Console.WriteLine(num & " is not a Prime Number!")
        Else
            Console.WriteLine(num & " is a Prime Number!")
        End If
    Else
        Console.WriteLine("Invalid Number!")
    End If
    Stop_Time = Now
    Elapsed_Time = Stop_Time.Subtract(Start_Time)
    Return Elapsed_Time.TotalSeconds.ToString("0.000000")
End Function