How do I get my C# custom class array to correctly track member elements?

I'm trying to achieve the following - When a user enters a barcode in ProductsListCBX, the app should look up the product and load the product info. My custom class has a field ItemCount, and I have an array TransactionRecord[50] that stores each transaction's info (ItemCount, ItemName, ItemUnitCost) as a record of the array. My issue is the ItemCount field seems to be retaining the ItemCount from the last transaction when it should initialize each new record of the array with an ItemCount = 0. The item count just increases sequentially as I loop through the array (displaying them gives 1, 2, 3, ... when it should have a default of 1, 1, 1, ... ). When adding a new transaction, if the barcode matches a barcode that's already in one of the transactions, then the app should just increase the ItemCount for that transaction. Am I doing something wrong with my code? Please assist, I've provided the code below.

using System.IO;
using System.Drawing;
using System.Windows.Forms;
using System.Drawing.Printing;
namespace MyApp
{
public partial class POSHubForm : Form
{
public POSHubForm(string username, string org)
{
InitializeComponent();
UsernameLBL.Text = username;
CompanyLBL.Text = org;
}
Transaction[] TransactionRecord = new Transaction[50];
readonly Product SaleItem = new Product();
string saleString = String.Empty;
string MasterSaleString = String.Empty;
string footerString = String.Empty;
double MasterCost = 0;
double totalCost = 0;
int salesCount = 0;
int RecordCount = 0;
int AllTempTotal = 0;
int TempTotal = 0;
int TotalSalesToday = 0;
private void CreateTransactionRecord()
{         
if (ProductListCBX.Text != String.Empty)
{
try
{
string itemDataLocation = "D:\\MyApp\\Barcodes\\" + ProductListCBX.Text + ".txt";
TransactionRecord[RecordCount] = new Transaction();
SaleItem.LoadProduct(itemDataLocation);
saleString += SaleItem.GetPaddedName() + "E" + String.Format("{0:0.00}", SaleItem.GetPrice()) + "\n";
MasterSaleString += SaleItem.GetPaddedName() + "E" + String.Format("{0:0.00}", SaleItem.GetPrice()) + "\n";
ProductInfoLBL.Text = SaleItem.GetName();
totalCost += SaleItem.GetPrice();
MasterCost += SaleItem.GetPrice();
TotalCostLBL.Text = "E" + String.Format("{0:0.00}", totalCost);
ItemCostLBL.Text = "E" + String.Format("{0:0.00}", SaleItem.GetPrice());
salesCount++;
CountBtn.Text = Convert.ToString(salesCount);
for (int k = 0; k <= RecordCount ; k++)
{
if(Convert.ToInt64(ProductListCBX.Text) == TransactionRecord[k].GetBarCode())
{
TransactionRecord[k].IncreaseItemCount();
}
else
{
TransactionRecord[RecordCount].IncreaseItemCount();
TransactionRecord[RecordCount].SetBarCode(Convert.ToInt64(ProductListCBX.Text));
TransactionRecord[RecordCount].SetUnitPrice(Convert.ToDouble(SaleItem.GetPrice()));
TransactionRecord[RecordCount].SetItemName(SaleItem.GetName());
TransactionRecord[RecordCount].SetTotalPrice();
}
}
string Record = String.Empty;
string Items = String.Empty;
for (int n = 0; n <= RecordCount; n++)
{
Record += TransactionRecord[n].CreateSaleRecord();
Items += Convert.ToString(TransactionRecord[n].GetItemCount()) + ", ";
}
MessageBox.Show(Record + "\n\n" + Items);
RecordCount++;
ItemDescriptionTBX.Text += "  > " + SaleItem.GetName().PadRight(30) + "E" + String.Format("{0:0.00}", SaleItem.GetPrice()) + "\r\n";
}
catch (FileNotFoundException)
{
MessageBox.Show("The product you entered does not exist");
}
catch (Exception x)
{
MessageBox.Show(x.Message);
}
}
else
{
MessageBox.Show("Item list cannot be empty. Type, browse, or scroll the item list to add products for a sale.");
}
ProductListCBX.Text = String.Empty;
}
}
}
//EDIT - This is the Transaction class
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace MyApp
{
class Transaction
{
private long ItemBarCode;
private double ItemUnitPrice = 0;
private double ItemTotalPrice = 0;
private string ItemName = String.Empty;
private int ItemCount = 0;
public long GetBarCode()
{
return ItemBarCode;
}
public string GetItemName()
{
return ItemName;
}
public int GetItemCount()
{
return ItemCount;
}
public double GetUnitPrice()
{
return Convert.ToDouble(ItemCount * ItemUnitPrice);
}
public double GetTotalPrice()
{
return Convert.ToDouble(ItemCount * ItemUnitPrice);
}
public string CreateSaleRecord()
{
return Convert.ToString(ItemCount).PadRight(3) + " x " + ItemName.PadRight(50) + "- E" + String.Format("{0:0.00}", GetTotalPrice()) + "\n";
}
public void ReverseItem()
{
}
public void IncreaseItemCount()
{
ItemCount++;
}
public void DecreaseItemCount()
{
ItemCount--;
}
public void SetBarCode(long Code)
{
ItemBarCode = Code;
}
public void SetItemName(string Name)
{
ItemName = Name;
}
public void SetUnitPrice(double Price)
{
ItemUnitPrice = Price;
}
public void SetTotalPrice()
{
ItemTotalPrice = Convert.ToDouble(ItemCount * ItemUnitPrice);
}
}
}
</details>
# 答案1
**得分**: 0
以下是您的类的一些调整。由于没有太多的验证逻辑，我们肯定可以将您的get和set方法合并为自动属性。这使得类更加紧凑且更容易使用。
```csharp
public class Transaction
{
public long ItemBarCode { get; set; }
public string ItemName { get; set;} = string.Empty;
public uint ItemCount { get; set; } = 1;
//这两者可以是decimal类型，也可以是double，随您决定
public double ItemUnitPrice { get; set; }
public double ItemTotalPrice => ItemCount * ItemUnitPrice; //这是一个只读属性，可以将其视为getter方法。这是一个计算值，没有真正需要setter方法
//通过格式化插值字符串，可以使下面的方法更加清晰，详见：https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/tokens/interpolated
public string CreateSaleRecord() => Convert.ToString(ItemCount).PadRight(3) + " x " + ItemName.PadRight(50) + "- E" + String.Format("{0:0.00}", GetTotalPrice()) + "\n";
public void ReverseItem()
{
//未提供内容，保持原样
}
}

让我们总结一下关键更改 public uint ItemCount { get; set; } = 1;

1. 您可以通过 transaction.ItemCount 访问这个属性。
2. 现在可以使用 transaction.ItemCount++ 和 transaction.ItemCount-- 来增加和减少计数。由于这是无符号整数 uint，不应该减到负值，因此请确保有服务逻辑来阻止这种情况发生。
3. 注意末尾的 = 1。这确保了在创建新对象时，此属性将初始化为1。我不确定为什么您最初将值初始化为0，如果您更喜欢从1开始，可以这样做。

话虽如此，这实际上应该使用类似 Dictionary<long, Transaction> 来正确查找确切的记录。您当前正在使用全局变量 RecordCount 来跟踪数组中的当前位置，但这是非常不必要的复杂性。

我对逻辑有点困惑，但似乎您正在搜索记录以查看该产品是否存在，如果存在，则增加计数。如果不存在，则简单地“添加”一个新事务（实际上是覆盖了记录在 RecordCount 索引处的内容）。简化所有这些：首先尝试读取和更新记录，如果失败，则将记录添加到字典中。

Dictionary<long, Transaction> records = new(); //键 = 条形码
//在这里添加记录

if (long.TryParse(ProductListCBX.Text, out long textCode))
{
    if (records.ContainsKey(textCode)) 
    {
        records[textCode].ItemCount++;
    }
    else 
    {
        records.Add(new Transaction()
        {
            //item count is already init to 1
            ItemBarCode = textCode,
            ItemUnitPrice = SaleItem.Price,
            ItemName = SaleItem.Name,
            //total price is available on-demand, no need to set
        });
    }
}
else
{
    //处理无法解析的情况
}

非常重要的是，字典在查找操作上具有常数时间复杂度，而不是在每次需要更新记录集合时执行搜索操作。永远不需要全局变量手动跟踪数组中当前要处理的记录。如果条形码保证是唯一的，那么它是作为字典键的完美候选者。

public class Transaction
{
    public long ItemBarCode { get; set; }
    public string ItemName { get; set;} = string.Empty;
    public uint ItemCount { get; set; } = 1;

    //these both can be decimal type, or double, your call
    public double ItemUnitPrice { get; set; }
    public double ItemTotalPrice => ItemCount * ItemUnitPrice; //this is a readonly property, imagine this as a getter method. This is a computed value, there is no real need for a setter method

    //the following method could be made a bit cleaner by formatting interpolated strings, read: https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/tokens/interpolated
    public string CreateSaleRecord() => Convert.ToString(ItemCount).PadRight(3) + " x " + ItemName.PadRight(50) + "- E" + String.Format("{0:0.00}", GetTotalPrice()) + "\n";

    public void ReverseItem()
    {
        //nothing provided, left as is
    }
}

Dictionary<long, Transaction> records = new(); //key = bar code
//add records here

if (long.TryParse(ProductListCBX.Text, out long textCode))
{
    if (records.ContainsKey(textCode)) 
    {
        records[textCode].ItemCount++;
    }
    else 
    {
        records.Add(new Transaction()
        {
            //item count is already init to 1
            ItemBarCode = textCode,
            ItemUnitPrice = SaleItem.Price,
            ItemName = SaleItem.Name,
            //total price is available on-demand, no need to set
        });
    }
}
else
{
    //Handle scenario if you could not parse
}