在 C# 中创建对象的副本 [英] Creating a copy of an object in C#

问题描述

请看下面的代码(摘自一本 C# 书籍):

Please have a look at the code below (excerpt from a C# book):

public class MyClass 
{
    public int val;
}
public struct myStruct 
{
    public int val;
}
public class Program 
{
    private static void Main(string[] args) 
    {
        MyClass objectA = new MyClass();
        MyClass objectB = objectA;

        objectA.val = 10;
        objectB.val = 20;

        myStruct structA = new myStruct();
        myStruct structB = structA;

        structA.val = 30;
        structB.val = 40;

        Console.WriteLine("objectA.val = {0}", objectA.val);
        Console.WriteLine("objectB.val = {0}", objectB.val);
        Console.WriteLine("structA.val = {0}", structA.val);
        Console.WriteLine("structB.val = {0}", structB.val);

        Console.ReadKey();
    }
}

我知道它会产生以下输出:

I understands it produces the output below:

objectA.val = 20
objectB.val = 20
structA.val = 30
structB.val = 40

输出的最后两行我没有问题，但前两行告诉我 objectA 和 objectB 指向同一个内存块(因为在C#，对象是引用类型).

The last two lines of the output I have no problem with, but the first two tell me that objectA and objectB are pointing to the same memory block (since in C#, objects are reference types).

问题是如何制作objectB，一个objectA 的副本，以便它指向内存中的不同区域.我知道尝试分配他们的成员可能不起作用，因为这些成员也可能是参考.那么我如何让 objectB 成为一个与 objectA 完全不同的实体?

The question is how do make objectB, a copy of objectA so that it points to a different area in memory. I understand that trying to assign their members may not work since those members may be references, too. So how do I go about making objectB a completely different entity from objectA?

推荐答案

没有内置的方式.您可以让 MyClass 实现 IClonable 接口(但它有点过时)或只编写您自己的 Copy/Clone 方法.无论哪种情况，您都必须编写一些代码.

There is no built-in way. You can have MyClass implement the IClonable interface (but it is sort of deprecated) or just write your own Copy/Clone method. In either case you will have to write some code.

对于大对象，您可以考虑序列化 + 反序列化(通过 MemoryStream)，只是为了重用现有代码.

For big objects you could consider Serialization + Deserialization (through a MemoryStream), just to reuse existing code.

无论采用何种方法，请仔细考虑副本"的确切含义.它应该走多深，是否有要排除的Id字段等.

Whatever the method, think carefully about what "a copy" means exactly. How deep should it go, are there Id fields to be excepted etc.

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