c# - 如何获取列表框中商品的价格总和？

Question

按钮1-10为项目； the pos screenshot

我使用过但不起作用的代码也许是错误的，但我在互联网上找不到答案

private void enterPayment_Click(object sender, EventArgs e)
{
    label1.Text = "Payment";
    //price.ReadOnly = false;
    //price.Text = "0.00";
    //price.Focus();

    //Kukunin ko yung total ng List Items
    double total = 0;
    int ilan = orders.Items.Count;

    for (int i = 0; i >= ilan; i++)
    {
        string item = orders.Items[i].ToString();
        int Index = item.IndexOf("@");
        int Length = item.Length;
        string presyoString = item.Substring(Index + 1, Length - Index - 1);
        double presyoDouble = double.Parse(presyoString);
        total += presyoDouble;
        //price.Text = (total + ".00");
    }
    price.Text = (total + ".00");
}

Answer 1

我强烈建议您仅将列表框用作 View ，而不是用于执行数学运算。这些数据可以用在List等集合中，以便更好的进行操作。

例如，在程序加载时，我将在List<T>上添加产品信息。在表单上，​​我在按钮中放置一个标签，将其视为产品 ID。因此，当我单击按钮时，它将传递标签属性，然后从那里，我将搜索列表上有关我的 ID 的产品信息，并添加到另一个最终 List<T> 中。并求其总和。

public partial class Form1 : Form
{
    private List<ProductDisplay> listProductDisplay = new List<ProductDisplay>();
    private List<ProductInformation> listProductInfo = new List<ProductInformation>();
    public Form1()
    {
        InitializeComponent();
        LoadProduct();

    }
    private void LoadProduct()
    {
        listProductDisplay = new List<ProductDisplay>()
        {
            new ProductDisplay{ProdID = 1,ProdName = "Chargrilled Burger",ProdPrice = 330.00m},
            new ProductDisplay{ProdID = 2,ProdName = "Mushroom N' Swish",ProdPrice = 330.00m},
            new ProductDisplay{ProdID = 3,ProdName = "Chicken Burger",ProdPrice = 250.00m},
            new ProductDisplay{ProdID = 4,ProdName = "Steak Loader",ProdPrice = 220.00m},
            new ProductDisplay{ProdID = 5,ProdName = "Cookie Sandwich",ProdPrice = 125.00m},
            new ProductDisplay{ProdID = 6,ProdName = "Cookie Sundae",ProdPrice = 175.00m},
            new ProductDisplay{ProdID = 7,ProdName = "Chicken Nuggets",ProdPrice = 145.00m},
            new ProductDisplay{ProdID = 8,ProdName = "Curly Fries",ProdPrice = 75.00m},
            new ProductDisplay{ProdID = 9,ProdName = "Sprite",ProdPrice = 50.00m},
            new ProductDisplay{ProdID = 10,ProdName = "Coke",ProdPrice = 50.00m}
        };
    }

    private void InsertOrder_ButtonClick(object sender, EventArgs e)
    {
        try
        {
            Button btn = (Button)sender;
            int number = Convert.ToInt32(btn.Tag);
            var itemProduct = listProductDisplay.First(x => x.ProdID == number);
            ProductInformation prod = new ProductInformation
            {
                ProdID = itemProduct.ProdID,
                ProdName = itemProduct.ProdName,
                ProdPrice = itemProduct.ProdPrice,
                ProdQty = 1

            };
            prod.ProdDisplayName = $"{prod.ProdQty}x {prod.ProdName} @{prod.ProdPrice.ToString("F")} = {(prod.ProdPrice * prod.ProdQty).ToString("F")}";
            listProductInfo.Add(prod);
            listBoxItem.DataSource = null;
            listBoxItem.DataSource = listProductInfo;
            listBoxItem.DisplayMember = "ProdDisplayName";
            listBoxItem.ValueMember = "ProdID";

            var price = listProductInfo.Sum(t => (t.ProdPrice * t.ProdQty));
            txtPayment.Text = price.ToString("F");
        }
        catch (Exception ex)
        {
            MessageBox.Show("Failed to insert order");
            throw;
        }
    }
}
public class ProductDisplay
{
    public int ProdID { get; set; }
    public string ProdName { get; set; }
    public decimal ProdPrice { get; set; }
}
public class ProductInformation
{
    public int ProdID { get; set; }
    public string ProdName { get; set; }
    public string ProdDisplayName { get; set; }
    public decimal ProdPrice { get; set; }
    public int ProdQty { get; set; }
}