PV 函数和移植 VB6 到 C#

Question

I'm working on porting some classic VB6 code to C# and just stumbled across a usage of the PV function.

I feels wrong including a reference to the Microsoft.VisualBasic Assembly. Is this something that is commonly done, or should I explore further options. The next idea that pops into my mind is exploring this PV function in Reflector.

Answer 1

The use of Microsoft.VisualBasic from C# and VB.NET has been discussed thoroughly under this question . The Microsoft.VisualBasic namespace is fully supported , and will be around as long as .Net is around. There's no reason to avoid it.

EDIT: It's telling that at the time of typing, the other answers for this question are an incorrect reimplementation of the function, and a one-man-band unsupported library from Code Galleries. Come on guys, it would take a real major event for Microsoft to drop the financial functions from VB.

It's a different story for Microsoft.VisualBasic.Compatibility , which is exclusively for use by the VB6 upgrade wizard, EDIT has now been marked obsolete in .Net 4 (my prediction came true), and should not be used for new development. There would be some advantages in removing references to this, but personally I'd probably try to achieve a fully working port first referencing.Net 3.5.

Answer 2

Pretty straight forward to replicate in C#

    public static double PV(double Rate, int nPer, double Pmt, double FV, bool Type)
    {
        double ann = Math.Pow(1 + Rate, nPer);
        return -(FV + Pmt * (1 + (Type ? Rate : 0)) * ((ann - 1) / Rate)) / ann;
    }

Just a re-arrangement of the formula Microsoft provides .

Answer 3

You could use this library that duplicates excel functions in f#

Library

It has PV which is present value. I have used it once or twice. Just drop it in and add the reference.

Answer 4

I tried using the accepted answer, but I couldn't get it to work in .NET Core. I did some looking around and ran across this code on github that appears to be Microsoft's implementation of PV:

https://github.com/microsoft/referencesource/blob/master/Microsoft.VisualBasic/runtime/msvbalib/Financial.vb#L662

    Public Function PV(ByVal Rate As Double, ByVal NPer As Double, ByVal Pmt As Double, Optional ByVal FV As Double = 0, Optional ByVal Due As DueDate = DueDate.EndOfPeriod) As Double

        Dim dTemp As Double
        Dim dTemp2 As Double
        Dim dTemp3 As Double

        If Rate = 0.0# Then
            Return (-FV - Pmt * NPer)
        Else
            If Due <> 0 Then
                dTemp = 1.0# + Rate
            Else
                dTemp = 1.0#
            End If
            dTemp3 = 1.0# + Rate

            '       WARSI Using the exponent operator for pow(..) in C code of PV. Still got
            '       to make sure that they (pow and ^) are same for all conditions
            dTemp2 = dTemp3 ^ NPer

            'Do divides before multiplies to avoid OverFlowExceptions
            Return (-(FV + Pmt * dTemp * ((dTemp2 - 1.0#) / Rate)) / dTemp2)
        End If

    End Function

You'd still need to transpile it to C#. If I have a general enough implementation at the end of this I'll post that too.