C#中的引用类型 [英] Reference type in C#

问题描述

考虑这个代码:

public class Program
{
    private static void Main(string[] args)
    {
        var person1 = new Person { Name = "Test" };
        Console.WriteLine(person1.Name);

        Person person2 = person1;
        person2.Name = "Shahrooz";
        Console.WriteLine(person1.Name); //Output: Shahrooz
        person2 = null;
        Console.WriteLine(person1.Name); //Output: Shahrooz
    }
}

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

显然，当将person1赋值给person2，并且person2的Name属性发生变化时，person1 的 >Name 也将被更改.person1 和 person2 具有相同的引用.

Obviously, when assigning person1 to person2 and the Name property of person2 is changed, the Name of person1 will also be changed. person1 and person2 have the same reference.

为什么当person2 = null时，person1变量也不为null?

Why is it that when person2 = null, the person1 variable will not be null either?

推荐答案

person 和 person2 都是对同一个对象的引用.但这些是不同的参考.所以当你跑步时

Both person and person2 are references, to the same object. But these are different references. So when you are running

person2 = null;

你只改变了引用person2，而保持引用person和对应的对象不变.

you are changing only reference person2, leaving reference person and the corresponding object unchanged.

我想解释这一点的最好方法是使用简化的插图.以下是之前 person2 = null的情况:

I guess the best way to explain this is with a simplified illustration. Here is how the situation looked like before person2 = null:

这是空赋值之后的图片:

And here is the picture after the null assignment:

如您所见，在第二张图片中，person2 没有引用任何内容(或 null，严格来说，因为没有引用任何内容并且引用了 null是不同的条件，请参阅 Rune FS 的评论)，而 person 仍然引用现有的对象.

As you can see, on the second picture person2 references nothing (or null, strictly speaking, since reference nothing and reference to null are different conditions, see comment by Rune FS), while person still references an existing object.

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