为列表框中的每个项目添加价格 - C# .Net、Windows 窗体应用程序

Question

I am trying to build an windows forms application with c#. The main functionality of the application is that it is going to allow the user to add items to a shopping cart (an listbox probably) and sum up (to a Label Text) the total price for the products added to this cart. Also, a product can be added more than once. So basically it can be called a shopping cart app.

My question here is, how can I calculate the total price of items added to the shopping cart? Because, first of all, I have added all the products to this listbox as a list of strings (with Listbox.Items.Add("Product1") . So I don't know how to add a price for each product (string element of this list), and later be able to add it up.

Should I somehow add the products as objects of type Product Class (with 2 properties, name and price)? If so, how do I pass just the name property to the list of listbox items?

So far, here is some of my main code:

public Form1()
{
    InitializeComponent();
    Product products = new Product();
    AddProducts(); 
}

List<string> productList = new List<string>();

public void AddProducts()
{
    productNames.Add("Product X");
    productNames.Add("Product Z");

    foreach (var product in productList) 
    {
        ProductListBox.Items.Add(product);
    }
}

Answer 1

The first thing to do is to define the Product class with two separate properties, one for the Name and one for the Price .
Then override the ToString() method to return in a single string both the Name and the Price converted to a string or just the Name.

This override is required if you want to display the Products names and their price in a single line displayed in the ListBox. Indeed, the ListBox control, when bound through a DataSource, looks at the ToString method of the bound class to represent its items.

public class Product
{ 
    public string Name { get; set; }
    public decimal Price { get; set; }

    // This returns both Name and Price, but, of course, if you want only
    // the name just return $"{Name}"
    public override string ToString()
    {
        return $"{Name} - {Price.ToString("C")}";
    }
}

Now, in your form constructor, you could create the list of products (statically in this example) and pass that list to the ListBox's DataSource property.
Finally the task to compute the total is just a simple Linq call to the Sum extension and pass the result to the Label text property.

List<Product> products = new List<Product>();
public Form1()
{
    InitializeComponent();
    AddProducts(); 
    ProductListBox.DataSource = products;
    labelTotalPrice.Text = products.Sum(x => x.Price).ToString("C");
}

public void AddProducts()
{
    products.Add(new Product {Name = "Product X", Price = 10.4m});
    products.Add(new Product {Name = "Product Z", Price = 1.5m});
    products.Add(new Product {Name = "Product K", Price = 7.32m});
}