关闭捕捉变量修改原始以及 [英] Closure captured variable modifies the original as well

问题描述

我有以下简单的code：

I have the following simple code:

static void Main(string[] args)
{
    int j = 0;
    Func<int> f = () =>
    {
        for (int i = 0; i < 3; i++)
        {
            j += i;
        }
        return j;
    };

    int myStr = f();
    Console.WriteLine(myStr);
    Console.WriteLine(j);
    Console.Read();
}

从我读涉及关闭的时候，一个新的类型由编译器生成的，因此它可以存储所捕获的变量，并保持对它的引用。然而，当我运行下面的code，这两种印刷线显示3。我期待0和3，因为匿名方法由编译器生成的类都有其自己的变量。那么，为什么它还要修改以外的变量？

From what I read when closures are involved, a new type is created by the compiler so it can store the captured variable and maintain a reference to it. However, when I run the following code, both printed lines show 3. I was expecting 0 and 3, because the anonymous method has its own variable in the generated class by the compiler. So why does it also modify the outside variable?

推荐答案

外面的变量，并在封闭的变量是的相同的变量的。你的程序是等价于：

The outside variable and the variable in the closure are the same variable. Your program is equivalent to:

private class Closure
{
    public int j;
    public int Method()
    {
        for (int i = 0; i < 3; i++)
        {
            this.j += i;
        }
        return this.j;
    }
}
static void Main(string[] args)
{
    Closure closure = new Closure();
    closure.j = 0;
    Func<int> f = closure.Method;
    int myStr = f();
    Console.WriteLine(myStr);
    Console.WriteLine(closure.j);
    Console.Read();
}

现在是明确为什么你所观察到的结果呢？

Now is it clear why you get the observed result?

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