我正在尝试计算易货系统，所以首先我将项目添加到库存（json文件）另一种方法...然后尝试计算CalCost方法中的最小最大价格数组，并发送到howmuch方法，如下所示

[WebMethod]
    public double[] CalInstrumentCost(String instrumentName, double instrumentQuantity)
    {
        double[] priv = new double[2];

        try
        {

            string jsonString = File.ReadAllText(filePath);
            MusicInstrumentsList Mlist = JsonConvert.DeserializeObject<MusicInstrumentsList>(jsonString);
            var MInstrument = Mlist.MusicInstruments_List.Find(item => item.InstrumentsName == instrumentName);

            if (MInstrument != null)
            {

                double miprice = MInstrument.MinInstrumentPrice * instrumentQuantity;
                double maPrice = MInstrument.MaxInstrumentPrice * instrumentQuantity;

                priv[0] = miprice; // min Price
                priv[1] = maPrice; // max Price

                return priv;  
            }
            else
            {
                throw new InvalidOperationException("Invalid Operation");
            }
        }
        catch
        {
            throw new InvalidOperationException("Invalid Operation");
        }
    }

但priv不存在，所以我尝试全局定义，但计算结果是INF（1/0 = ⇒ nf），我该怎么办？

[WebMethod]
    public double HowMuchInstrument(String instrumentName, double totalBudget)
    {
        double result = 0;


        try
        {
            string jsonString = File.ReadAllText(filePath);
            MusicInstrumentsList Mlist = JsonConvert.DeserializeObject<MusicInstrumentsList>(jsonString);
            var MInstrument = Mlist.MusicInstruments_List.Find(item => item.InstrumentsName == instrumentName);

            if (MInstrument != null)
            {
                result = Math.Floor(totalBudget / priv[0]);
            }
            else
            {
                return result;
            }
        }
        catch
        {
            return result;
        }
        return result;
    }