用C枚举值的内存位置 [英] Memory location of enum value in C

问题描述

我想我读的地方，是非法采取枚举值的地址在C（不是左值枚举值;不过，我现在找不到这方面的消息）。这种说法是否正确，如果是这样，为什么？

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编辑：

下面是一个例子来阐明我的意思是枚举值之上。我的意思是服用 FIRST_VALUE 下面的地址，而不是采取一个枚举的实际实例的地址：

 枚举myenum
{
    FIRST_VALUE，
    SECOND_VALUE
};
 

解决方案

枚举值是有些模棱两可;不过，我想你指的是以下内容：

 枚举myenum
{
    FIRST_VALUE，
    SECOND_VALUE
};
 

在这种情况下，它是违法的 FIRST_VALUE 的地址。这样做的原因是， FIRST_VALUE 实际上并不存在于存储器中的任何...它仅仅是一个常数，有效地别称数字0（当然，中，你也不能走地址）。

如果，在另一方面，你的意思是你是否可以采取被声明为枚举变量的地址：

 枚举myenum X;
枚举myenum * mypointer =安培; X;
 

那么这绝对是可能的。

I think I've read somewhere that it is illegal to take the address of an enum value in C (enum values not being lvalues; however, I can't find any information on this now). Is that correct and, if so, why?

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Edit:

Here's an example that clarifies what I mean by "enum value" above. I mean taking the address of first_value below, not taking the address of an actual instance of an enum:

enum myenum
{
    first_value,
    second_value
};

解决方案

"Enum value" is slightly ambiguous; however, I assume you mean the following:

enum myenum
{
    first_value,
    second_value
};

In this case, it is illegal to take the address of first_value. The reason for this is that first_value does not actually exist in memory anywhere... it is just a constant, effectively another name for the number 0 (of which, of course, you also cannot take the address).

If, on the other hand, you mean whether you can take the address of a variable that is declared as an enum:

enum myenum x;
enum myenum *mypointer=&x;

then that is definitely possible.

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