为什么堆栈数据在分配 C# 之前会被修改

Question

我当前的项目确实遇到了一个奇怪的问题。我有示例类，它将保存一些数据作为一个集合 (List<SampleData>)。并且我使用了另一个堆栈集合 (Stack<SampleData>) 来记录添加到第一个列表的数据。修改第一个列表的第一个索引数据后，在我不知情的情况下修改了堆栈数据

public class ActionLog
    {
        private Stack<SampleData> UndoStack;
        public ActionLog()
        {
            UndoStack = new();
        }
        public void Log(SampleData Data)
        {
            UndoStack.Push(Data);
            foreach (var item in UndoStack)
                System.Console.WriteLine($"{item.Name}");
        }
    }
public class ActivityControl
    {
        public ActionLog Logger { get; set; } = new ActionLog();
        public List<SampleData> Datas { get; set; } = new List<SampleData>();
        public void Initiallize(List<SampleData> datas)
        {
            Datas.AddRange(datas);
            Logger.Log(datas[0]);
        }
    }
 internal class Program
    {
        static ActivityControl contorl = new ActivityControl();
        static void Main(string[] args)
        {
            List<SampleData> list = new List<SampleData>();
            SampleData data = new SampleData()
            {
                Name = "Data 1"
            };
            SampleData data2 = new SampleData()
            {
                Name = "Data 2"
            };
            list.Add(data);
            list.Add(data2);
            contorl.Initiallize(list);
            contorl.Datas[0].Name = "Data 11";
            contorl.Logger.Log(new SampleData() { Name = "Fake Data" });
            Console.ReadKey();
        }
    }

以上代码的输出应该是：Data 1 , Fake Data, Data 1 but i am seeing Data 1, Fake Data, Data 11

Answer 1

我遇到的问题与深拷贝和浅拷贝有关。我在 SampleData class 中添加了一个 List<SampleData>DeepCopy() 方法，然后在首次分配时调用该方法。以下代码解决了该问题：

public class SampleData
    {
        public string Name { get; set; }
        public SampleData DeepCopy()
        {
            var copy = new SampleData();
            copy.Name = this.Name;
            return copy;
        }
    }
public class ActionLog
    {
        private Stack<List<SampleData>> UndoStack;
        public ActionLog()
        {
            UndoStack = new();
        }
        public void Log(List<SampleData> Data)
        {

            UndoStack.Push(Data);
            foreach (var item in UndoStack)
                System.Console.WriteLine($"{item[0].Name}");
        }
    }
public class ActivityControl
    {
        public ActionLog Logger { get; set; } = new ActionLog();
        public List<SampleData> Datas { get; set; }

        public void Initiallize(List<SampleData> datas)
        {
            Datas = datas;
            List<SampleData> datas1 = new List<SampleData>();
            foreach (var dt in Datas)
            {
                datas1.Add(dt.DeepCopy());
            }

            Logger.Log(datas1);
        }
    }
internal class Program
    {
        static ActivityControl contorl = new ActivityControl();
        static void Main(string[] args)
        {
            List<SampleData> list = new List<SampleData>();
            SampleData data = new SampleData()
            {
                Name = "Data 1"
            };
            SampleData data2 = new SampleData()
            {
                Name = "Data 2"
            };
            list.Add(data);
            list.Add(data2);
            contorl.Initiallize(list);
            contorl.Datas[0].Name = "Data 11";
            contorl.Logger.Log(contorl.Datas);
            Console.ReadKey();
        }
    }

为什么堆栈数据在分配 C# 之前会被修改

Why would Stack data modified before it gets assigned C#

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