参考在C＃中的变量？ [英] References to variables in C#?

问题描述

在C ++中，我可以做这样的事情：

In C++, I can do something like this:

int i[10] = new int[10];
int *p = &i[5];

然后，我可以随时知道p指向int数组我的第5个元素，无论我的内容。

Then, I can always know that p points to the 5th element of int array i, regardless of i's contents.

有没有办法做到在C＃中类似的东西？

Is there any way to do something similar in C#?

我意识到这是可能的，其中C＃保护我们从我们自己的一种方式，所以我不是在寻找一个确切的equivelent，而是一个类似的概念...也就是说，能够指一些其他变量的内容，而不是变量本身的实例

I realize this is likely one of the ways in which C# "protects" us from ourselves, so i'm not looking for an exact equivelent, but rather a similar concept... that is, being able to refer to the contents of some other variable, rather than the instance of the variable itself.

下面是我使用的情况下我在想。我有一个字符串数组。我想有这些数组元素引用另一个数组。事情是这样的（显然不是有效的code）：

Here's my use case i'm thinking of. I have an array of strings. I would like to have another array of references to those array elements. Something like this (obviously not valid code):

string[] s = new string[] { "one", "two", "three", "four", "five", "six" };
stringref[] sr = new stringref[] { &s[0], &s[1], &s[2], &s[3], &s[4], &s[5] };

Console.WriteLine(sr[1]); // == "two"
s[1] = "two point zero";
Console.WriteLine(sr[1]); // == "two point zero"

当然，裁判paramets做到这一点，out参数让你写一个特定的变量。但对于非参数？你可以存储一个参考？你可以保持裁判的数组或字典？

Certainly, ref paramets do this, and out parameters allow you to write to a specific variable. But what about non-parameters? Can you store a ref? Can you keep an array of refs or a dictionary?

这似乎是如果与参数做到这一点的能力，是present，应该有办法做到这一点没有他们。

It seems like if the ability to do it with parameters is present, there should be a way to do it without them.

推荐答案

没有。把不安全 code不谈，这确实让持有指向的内存位置，有没有办法给一个变量的引用存放在C＃。

No. Putting unsafe code aside, which does allow holding pointers to memory locations, there's no way to store a reference to a variable in C#.

REF 和退出参数提供给需要参考的唯一手段，但你不能将它们保存在任何地方。

ref and out arguments provide the only means to take a reference but you can't save them anywhere.

您可以通过包装领域在类解除此限制，并使用其引用来代替。这是编译器捕捉封变量是什么：

You can workaround this limitation by wrapping fields in a class and using its reference instead. This is what the compiler does to capture variables in closures:

例如，当你写的：

int integer = 0;
Action<int> method = i => Console.WriteLine(i + integer);
integer = 42;
method(100); // prints 142, not 100

在第二行中，编译器将不得不采取了匿名方法，并将其存储在类一个单独的方法。显然，这种方法将无法获得整数变量。它在某种程度上需要一个参考，以整数变量传递给该匿名方法。由于它是不可能的，它会生成一个类与现场举行一个整数，并使用了类的实例来存储变量。基本上，本地变量被提升到一个场中的一类，并存储在堆

In the second line, the compiler will have to take out the anonymous method and store it as a separate method in the class. Obviously, that method won't have access to integer variable. It somehow needs to pass a "reference" to integer variable to that anonymous method. Since it's not possible, it'll generate a class with a field to hold an integer and uses an instance of that class to store the variable. Basically, the local variable is promoted to a field in a class and is stored in the heap.

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