我怎样才能正确地让我的 'Calculate' 按钮计算 ASP.NET C# 中的总价和折扣金额？

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);
                double DiscountPercentage= Convert.ToDouble(TextBox2.Text);
                double discountAmount = Convert.ToDouble(Label1.Text);
                double TotalPrice = Convert.ToDouble(Label2.Text);
                double discountValue = this.CalculateDiscountValue(SalesPrice, DiscountPercentage, discountAmount);
                double TotalValue = this.TotalPriceCalculate(TotalPrice, SalesPrice, discountAmount);
                Label1.Text = discountValue.ToString("c");
                Label2.Text = TotalPrice.ToString("c"); 
            
            }
        }
        protected double CalculateDiscountValue(int SalesPrice, double DiscountPercentage, double discountAmount)
        {
            discountAmount = SalesPrice * DiscountPercentage;
            return discountAmount; 
        }

        protected double TotalPriceCalculate(double TotalPrice, int SalesPrice, double discountAmount)
        {
            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>

大家好，

我已经在 Web 应用程序中创建了一个 ASP.NET 4.6 Web 表单，并且我使用 C# 来实现一些 Web 服务器控件的功能，但是我无法理解为什么当我点击 'Calculate' 按钮，当我在文本框中输入销售价格和折扣百分比时，它不会计算相应标签中的 折扣金额和总价 以粗体显示。这是我的 Default.aspx 代码和 Default.aspx.cs (C#) 代码。我做错了什么？

Answer 1

通过查看您的代码，我确定您遇到了异常。您正在尝试将 Label1.Text 转换为 Double，但 Label1.Text 没有任何值。此外，您将该值传递给方法只是为了它被 returned。这没有意义。

如果您想 return 方法中的任何值，则不需要将其作为参数传递给该方法。

按如下方式更改您的代码。

protected void Button1_Click(object sender, EventArgs e)
{
    if (IsValid)
    {
        int SalesPrice = Convert.ToInt32(TextBox1.Text);
        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)
{
    doubl discountAmount = SalesPrice * DiscountPercentage;
    return discountAmount; 
}

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

这应该可以帮助您解决问题。

我怎样才能正确地让我的 'Calculate' 按钮计算 ASP.NET C# 中的总价和折扣金额？

How can I properly get my 'Calculate' button to calculate the total price and discount amount in ASP.NET C#?

c#

webforms

asp.net-4.6