Visual Basic

Public Shared Function GetPrimes(ByVal n As Integer) As Integer()
    Dim primes As New ArrayList
    'Print 1 at the start, don't add to primes!
    Debug.WriteLine(1)

    For i As Integer = 2 To n
        'Calculate the square root of i
        Dim root As Integer = CInt(Math.Sqrt(i))
        'Is this number a prime?
        Dim prime As Boolean = True
        'Go to each previously calculated prime
        For Each p As Integer In primes
            'Check to see if the prime is smaller than the square root
            If (p <= root) Then
                'Check if rounded division and not-rounded division are the same
                If (i / p) = (i \ p) Then
                    'Not a prime
                    prime = False
                    'No need to check any further
                    Exit For
                End If
            End If
        Next p

        If prime Then
            Debug.WriteLine(i)
            'Add the prime to the arraylist
            primes.Add(i)
        End If
    Next i

    'Insert 1 at the start of primes
    'Can't do that at the beginning, because 100 / 1 = 100 \ 1
    primes.Insert(0, 1)
    'Return the primes
    Return CType(primes.ToArray(GetType(Integer)), Integer())
End Function