关于引用/集合/值类型的另一个 C# 问题答案

【问题标题】：Another C# question about references/collections/value types关于引用/集合/值类型的另一个 C# 问题
【发布时间】：2010-10-03 11:25:30
【问题描述】：

我有以下代码：

public class Test
{
    public static void Main()
    {
        List<Person> list = new List<Person>();
        Person person = new Person() { Name="Chris" };
        list.Add(person);

        person = new Person(){ Name="Wilson the cat" };
        list.Add(person);

        Console.WriteLine(list[0].Name);
        Console.WriteLine(list[1].Name);
        Console.ReadLine();
    }
}

public class Person
{
    public string Name {get;set;}   
}

我的问题是第一人称实例去哪里了？ CLR 会在某处神奇地创建它的新实例吗？无论如何在列表之外引用它 - 例如方法完成后它会去哪里？使用什么方法将对象存储在集合中（共 4 个问题）。

【问题讨论】：

标签： c# .net stack heap-memory

【解决方案1】：

1) 它在堆上（如果 > 84K 则在大对象堆上）

2) 是的，创建了一个新实例。可以通过列表访问来引用。

3) 集合可能使用列表，但您不需要知道内部细节，除非您需要特定的速度或空间属性。

【讨论】：

在方法完成之前，Person person... 在堆栈上？我的问题更多的是关于通用列表而不是旧的堆栈/堆列表

【解决方案2】：

    List<Person> list = new List<Person>();

    Person person = new Person() { Name="Chris" };
    // your person object lives on the heap. The person variable is just
    // a pointer of that object on the heap. Note that the pointer lives
    // on the stack, and the object it points to lives on the heap.

    list.Add(person);
    // when you add your person to to the list, all it does it pass a
    // copy of the *pointer* to the list's method. List has access to this
    // object through the pointer.

    person = new Person(){ Name="Wilson the cat" };
    // new'ing up a instance of person creates another person object on
    // the heap. Note that this doesn't overwrite our original person created above,
    // because our original person sits in an entirely differently memory 
    // location.

    // We did, however overwrite our pointer variable by assigning it a new
    // location to point at. This doesn't affect the object we put into our
    // list since the list received a copy of our original pointer :)

    list.Add(person);

    Console.WriteLine(list[0].Name);
    // list[0] has a pointer to the first object we created


    Console.WriteLine(list[1].Name);
    // list[1] has a pointer to the second object we created.

    Console.ReadLine();

    // when this methods goes out of scope (i.e. when the stack frame is
    // popped), the pointers will be dropped from memory, and the objects
    // on the heap will no longer have any live references to them, so
    // they'll be eaten by the garbage collector.

【讨论】：