为什么折扣金额文本框和总价计算不正确？

Question

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace XEx02Quotation
{
    public partial class Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }
       
        protected void Button1_Click(object sender, EventArgs e)
        {
            if (IsValid)
            {
                int SalesPrice = Convert.ToInt32(TextBox1.Text);
                // When a user inputs an integer, I want it to be able to handle input of fractions
                // without getting an exception error. 



                // If a user inputs a whole number or fractional number (like 20.25), it should be able
                // to handle it.
                double DiscountPercentage = Convert.ToDouble(TextBox2.Text);
                

                double discountValue = this.CalculateDiscountValue(SalesPrice, DiscountPercentage);
                double TotalPrice = this.TotalPriceCalculate(SalesPrice, discountValue);
                Label1.Text = discountValue.ToString("c");
                Label2.Text = TotalPrice.ToString("c"); 
            
            }
        }
        protected double CalculateDiscountValue(int SalesPrice, double DiscountPercentage)
        {
           double discountAmount = SalesPrice * DiscountPercentage;
            return discountAmount; 
        }

        protected double TotalPriceCalculate(int SalesPrice, double discountAmount)
        {
            double TotalPrice = SalesPrice - discountAmount;
            return TotalPrice; 
        }


    }
        
}

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="XEx02Quotation.Default" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>Price quotation</title>
    <style type="text/css">
        .auto-style1 {
            width: 54%;
            height: 213px;
        }
        .auto-style15 {
            width: 114px;
            height: 23px;
        }
        .auto-style16 {
            width: 114px;
        }
        .auto-style17 {
            width: 114px;
            height: 28px;
        }
        .auto-style18 {
            width: 193px;
            height: 23px;
        }
        .auto-style20 {
            width: 193px;
            height: 28px;
        }
        .auto-style21 {
            width: 193px;
        }
        .auto-style22 {
            margin-left: 12px;
        }
        .auto-style23 {
            margin-left: 16px;
        }
        .auto-style25 {
            width: 193px;
            height: 5px;
        }
        .auto-style26 {
            width: 114px;
            height: 5px;
        }
        .auto-style27 {
            width: 143px;
            height: 23px;
        }
        .auto-style28 {
            width: 143px;
            height: 5px;
        }
        .auto-style29 {
            width: 143px;
        }
        .auto-style30 {
            width: 143px;
            height: 28px;
        }
        .auto-style31 {
            width: 143px;
            height: 25px;
        }
        .auto-style32 {
            width: 193px;
            height: 25px;
        }
        .auto-style33 {
            width: 114px;
            height: 25px;
        }
    </style>
</head>
<body>

    <form id="form1" runat="server">
        
        <h1>Price quotation</h1>
        
        <br />
        <br />
        <table class="auto-style1">
            <tr>
                <td class="auto-style27">Sales Price</td>
                <td class="auto-style18">
                    <asp:TextBox ID="TextBox1" runat="server" CssClass="auto-style23" Width="173px" Font-Bold="True"></asp:TextBox>
                </td>
                <td class="auto-style15"></td>
            </tr>
            <tr>
                <td class="auto-style27"></td>
                <td class="auto-style18"></td>
                <td class="auto-style15"></td>
            </tr>
            <tr>
                <td class="auto-style27">Discount percent</td>
                <td class="auto-style18">
                    <asp:TextBox ID="TextBox2" runat="server" CssClass="auto-style22" Width="169px"></asp:TextBox>
                </td>
                <td class="auto-style15"></td>
            </tr>
            <tr>
                <td class="auto-style28">Discount amount</td>
                <td class="auto-style25">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;<asp:Label ID="Label1" runat="server" Font-Bold="True" Text="Label"></asp:Label>
                </td>
                <td class="auto-style26"></td>
            </tr>
            <tr>
                <td class="auto-style27"></td>
                <td class="auto-style18"></td>
                <td class="auto-style15"></td>
            </tr>
            <tr>
                <td class="auto-style30">Total price</td>
                <td class="auto-style20">
                    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                    <asp:Label ID="Label2" runat="server" Font-Bold="True" Text="Label"></asp:Label>
                </td>
                <td class="auto-style17"></td>
            </tr>
            <tr>
                <td class="auto-style31">
                    </td>
                <td class="auto-style32"></td>
                <td class="auto-style33"></td>
            </tr>
            <tr>
                <td class="auto-style29">
                    <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Calculate" Width="90px" />
                </td>
                <td class="auto-style21">&nbsp;</td>
                <td class="auto-style16">&nbsp;</td>
            </tr>
        </table>
        
    </form>

</body>
</html>

当我在文本框中输入销售价格的分数（如 120.99）并在折扣百分比文本框中输入整数或双精度数（如 15 或 20.2）时，折扣金额和总价不计算正确的？我需要对我的变量进行显式转换吗？我感到很困惑。这是我的网络应用程序中 ASP.NET 网络表单的代码。我目前正在我的 Default.aspx.cs (C#) 文件中工作（我也有一个 Default.aspx 文件）。

Answer 1

正如评论和 TaW 的回答中所指出的，您应该使用 decimal 而不是 int 并且总价计算漏掉了 除法100。我把所有东西都放在一起了。

点击处理程序应修改如下：

 protected void Button1_Click(object sender, EventArgs e)
    {
        if (IsValid)
        {
            decimal salesPrice;
            decimal discount;

            if (decimal.TryParse(TextBox1.Text, out salesPrice))
            {
                if (decimal.TryParse(TextBox2.Text, out discount))
                {
                    decimal discountValue = this.CalculateDiscountValue(salesPrice, discount);
                    decimal totalPrice = this.TotalPriceCalculate(salesPrice, discount);

                    Label1.Text = discountValue.ToString("c");
                    Label2.Text = totalPrice.ToString("c");
                }
            }
        }
    }

辅助方法如下：

protected decimal CalculateDiscountValue(decimal salesPrice, decimal discountPercentage)
 {
    return salesPrice * discountPercentage / 100m;
 }

protected decimal TotalPriceCalculate(decimal salesPrice, decimal discountAmount)
 {
    return salesPrice - discountAmount;
 }

为什么折扣金额文本框和总价计算不正确？

How come the discount amount textbox and total price aren't calculating right?

c#

webforms

asp.net-4.6