Question

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了哪里？ CLR是否在某处神奇地创建了它的新实例？无论如何在列表之外引用它 - 例如该方法完成后它在哪里？使用什么方法在集合中存储对象（这是4个问题）。

Answer 1

    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.

Answer 2

1）它在堆上（或者如果＆gt; 84K那么大对象堆）

2）是的，创建了一个新实例。可以通过列表访问它来引用它。

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

关于引用/集合/值类型的另一个C＃问题

2 个答案: