c#更新多元素列表项目，如果项目已经存在，否则将其添加为新项目

使用c#，我试图创建一个包含多个元素的列表，如果主键不在列表中，则添加新项，否则更新项。我已经找到了相当多的每个部分，但我正在努力结合成一个可行的解决方案，我已经发现到目前为止。

下面是编译的注释代码。

问题:解决方案是将所有项目添加为新项目，即使密钥(ReceiptID)已经存在于列表中，因此我正在进行检查的方式存在问题。

可能是问题:(编辑:不是一个问题，因为它的工作如预期的)因为我还没能测试update if exist部分，我不知道我是否做对了。

任何指导都是感激的。

编辑:(注:根据WhoIsRich评论，这可以用字典代替列表来完成。这可能是一个更好、更有效的解决方案。由于WhoIsRich)。

using System;
using System.Collections.Generic;
using System.Linq;
namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            IList<Receipts> receiptList = new List<Receipts>()
            // The real app reads through a temporary table in the database
            // to pick up the line items of a sale. The objective is to combine those line
            // items into a summary list called receipts based on the receipt number. For this
            // runnable example, I add some data to the receipt list here.
            {
                new Receipts() { ReceiptID = 1, TotalPrice = 10, TotalCost = 5, Profit = 5, EmployeeID = 1 },
                new Receipts() { ReceiptID = 2, TotalPrice = 15, TotalCost = 6, Profit = 9, EmployeeID = 1 },
                new Receipts() { ReceiptID = 3, TotalPrice = 20, TotalCost = 7, Profit = 13, EmployeeID = 1 },
                new Receipts() { ReceiptID = 4, TotalPrice = 25, TotalCost = 10.50M, Profit = 14.50M, EmployeeID = 1 },
            };
            // some dummy data to update list item with.  Note: if receiptID is the same as one already in the list, employeeID
            // will also be the same. (It's always the same employee that completes a whole transaction).
            int[] receiptID = { 3, 4, 5, 5, 6, 7, 7, 8 };
            decimal[] totalPrice = { 5, 6, 7, 8, 9, 10, 11, 12 };
            decimal[] totolCost = { 2, 2.5M, 3, 3.5M, 4, 4.5M, 5, 5.5M };
            decimal[] profit = { 3, 3.5M, 4, 4.5M, 5, 5.5M, 6, 6.5M };
            int[] employeeID = { 1, 1, 1, 1, 2, 1, 1, 2 };
            // This for loop represents the while loop reading the database table
            for (int i = 0; i < 8; i++)
            {
                // first, check to see if the receiptID is already in the list. This is the 
                // part I am having trouble with.
                Receipts r = new Receipts();
//EDIT:
            //if (receiptList.Contains(new Receipts { ReceiptID = receiptID[i] }))  <== original in question
            //if (receiptList.Any(rc => rc.ReceiptID == receiptID[i])) <== Keyur PATEL's comment to question - Works
            //if (receiptList.Any(o => o.ReceiptID == receiptID[i])) <== kurakura88 answer - Works
            if (receiptList.Any(receipt => receipt.ReceiptID == receiptID[i])) // <== Eric Wu - Works
// END EDIT
                {
                    // The code never enters here! <<===  This is what I need help with fixing
                    var tu = receiptList.Single(x => x.ReceiptID == receiptID[i]);
                    tu.TotalPrice += totalPrice[i];
                    tu.TotalCost += totolCost[i];
                    tu.Profit += profit[i];
                    // receiptID and employeeID are not updated as they don't change in this if loop.
                }
                else
                {
                    // This should happen if the receiptID is not in the list, but it's happening
                    // every time.
                    r.ReceiptID = receiptID[i];
                    r.EmployeeID = employeeID[i];
                    r.TotalPrice = totalPrice[i];
                    r.TotalCost = totolCost[i];
                    r.Profit = profit[i];
                    receiptList.Add(r);
                }
            }
            // Below here just displays the results in a sorted maner which is working ok.
            var orderByValue = from s in receiptList
                               orderby s.ReceiptID
                               ascending
                               select s;
            foreach (var item in orderByValue)
            {
                Console.WriteLine("Receipt: {0} Employee: {1} TotalPrice: {2} TotalCost: {3} Profit: {4}", item.ReceiptID.ToString(), item.EmployeeID.ToString(), item.TotalPrice.ToString(), item.TotalCost.ToString(), item.Profit.ToString());
            }
            Console.ReadLine();
        }
    }
    public class Receipts
    {
        public int ReceiptID { get; set; }
        public int EmployeeID { get; set; }
        public decimal TotalPrice { get; set; }
        public decimal TotalCost { get; set; }
        public decimal Profit { get; set; }
    }
}
/*
The output I am getting is (note each sale line is added to list):
Receipt: 1 Employee: 1 TotalPrice: 10 TotalCost: 5 Profit: 5
Receipt: 2 Employee: 1 TotalPrice: 15 TotalCost: 6 Profit: 9
Receipt: 3 Employee: 1 TotalPrice: 20 TotalCost: 7 Profit: 13
Receipt: 3 Employee: 1 TotalPrice: 5 TotalCost: 2 Profit: 3
Receipt: 4 Employee: 1 TotalPrice: 25 TotalCost: 10.50 Profit: 14.50
Receipt: 4 Employee: 1 TotalPrice: 6 TotalCost: 2.5 Profit: 3.5
Receipt: 5 Employee: 1 TotalPrice: 7 TotalCost: 3 Profit: 4
Receipt: 5 Employee: 1 TotalPrice: 8 TotalCost: 3.5 Profit: 4.5
Receipt: 6 Employee: 2 TotalPrice: 9 TotalCost: 4 Profit: 5
Receipt: 7 Employee: 1 TotalPrice: 10 TotalCost: 4.5 Profit: 5.5
Receipt: 7 Employee: 1 TotalPrice: 11 TotalCost: 5 Profit: 6
Receipt: 8 Employee: 2 TotalPrice: 12 TotalCost: 5.5 Profit: 6.5
What want to get is (same receiptID's should have values added together to one item in list):
Receipt: 1 Employee: 1 TotalPrice: 10 TotalCost: 5 Profit: 5
Receipt: 2 Employee: 1 TotalPrice: 15 TotalCost: 6 Profit: 9
Receipt: 3 Employee: 1 TotalPrice: 25 TotalCost: 9 Profit: 16
Receipt: 4 Employee: 1 TotalPrice: 31 TotalCost: 13 Profit: 18
Receipt: 5 Employee: 1 TotalPrice: 15 TotalCost: 6.5 Profit: 8.5
Receipt: 6 Employee: 2 TotalPrice: 9 TotalCost: 4 Profit: 5
Receipt: 7 Employee: 1 TotalPrice: 21 TotalCost: 9.5 Profit: 11.5
Receipt: 8 Employee: 2 TotalPrice: 12 TotalCost: 5.5 Profit: 6.5
*/

修改if语句后，现在得到以下正确的结果:

Receipt: 1 Employee: 1 TotalPrice: 10 TotalCost: 5 Profit: 5
Receipt: 2 Employee: 1 TotalPrice: 15 TotalCost: 6 Profit: 9
Receipt: 3 Employee: 1 TotalPrice: 25 TotalCost: 9 Profit: 16
Receipt: 4 Employee: 1 TotalPrice: 31 TotalCost: 13.00 Profit: 18.00
Receipt: 5 Employee: 1 TotalPrice: 15 TotalCost: 6.5 Profit: 8.5
Receipt: 6 Employee: 2 TotalPrice: 9 TotalCost: 4 Profit: 5
Receipt: 7 Employee: 1 TotalPrice: 21 TotalCost: 9.5 Profit: 11.5
Receipt: 8 Employee: 2 TotalPrice: 12 TotalCost: 5.5 Profit: 6.5

receiptList.Contains(new Receipts { ReceiptID = receiptID[i] })

receiptList.Any(receipt=>receipt.ReceiptID == receiptID[i])