分配值时C＃中的折扣计算错误

Question

Can someone tell whats wrong with my code?

I've already tried casting first the value but I get the same result.

    /// <summary>
    /// Discount function
    /// </summary>
    /// <param name="ToDiscount">Price of an item</param>
    /// <param name="Discount">Discount</param>
    /// <param name="Type">Percent or Amount</param>
    /// <returns></returns>
    private decimal Discount(decimal ToDiscount, int Discount, DiscountType Type)
    {
        decimal temp = 0;
        try
        {
            if (Type == DiscountType.Percent)
            {
               int d = Convert.ToInt32((Discount / 100) * ToDiscount);
                decimal f = ToDiscount - d;
                temp = f;
            }
            else if (Type == DiscountType.Currency)
            {
                decimal FinalDiscount = ToDiscount - Discount;

                temp = FinalDiscount;
            }
        }
        catch (Exception ex)
        {
            Functions.ShowError(ex);
        }

        return temp;
    }

Example:

Discount(5000, 5, DiscountType.Percent);
//calculation: (5/100) * 5000 = 250
//discount: 5000 - 250 = 4750

but the with that function I've created I get result 5000. instead of 4750. I did break point on return temp; but when I hover this part int d = Convert.ToInt32((Discount / 100) * ToDiscount); no answer or no result.

Answer 1

Discount / 100 is performing integer division, in which the result is 0.

Hence (Discount / 100) * ToDiscount also is 0, resulting in nothing being subtracted from ToDiscount .

I think that the best thing for you to do would be to change the type of Discount to being a decimal , which would solve all of your problems there.

Answer 2

The line:

int d = Convert.ToInt32((Discount / 100) * ToDiscount);

Does integer arithmetic, where Discount / 100 will be zero for any discount between zero and 99.

You need to apply the discount via decimal, or floating point:

int d = Convert.ToInt32((Discount / 100m) * ToDiscount);

As an aside, naming a variable Type is probably going to cause a few readability headaches down the line.

Answer 3

When you make this: Convert.ToInt32((Discount / 100) * ToDiscount); you will have have 0 because:

Discount /100 = 0 (if discount is intm the result will be int)

you should do a calculation with double numbers