Question

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
};

Answer 1

“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.