C 循环双向链表，带有指向静态头地址的下一个/上一个指针的静态头初始化

Question

I want to initialize a Circular Doubly Linked List next/previous pointers to point at the address of a statically allocated element used as sentinel/first element. In this way, I can simplify the list operations. I tried the following code:

struct ErrorDataElement {
    struct ErrorDataElement *next;
    struct ErrorDataElement *prev;
    
    enum ErrorType type;
    int code;
    char **messages;
    char *file;
    char *function;
    int line;
} _errorList = { &_errorList, &_errorList, 0, -1, NULL, NULL, NULL, 0 };

When I print &_errorList memory address (in a sub-function called from main() function) I get a different address from _errorList.next and _errorList.prev .

_errorList.next and _errorList.prev have coherently the same value.

If I inspect using the following code:

printf("%d %d", _errorList.code, _errorList.next->code);

I see that _errorList.code = -1 as expected, while _errorList.next->code = 1001 , indicating to me that the value of _errorList.next has been initialized to some incorrect memory address. I suspect this is due to relative/absolute memory addressing during function initialization, but I can't figure out exactly and how to correctly initialize the static element, or whether or not is even possible such initialization.

Answer 1

I cannot reproduce your issue. When I execute this, it prints the expected result :

void afunc(struct ErrorDataElement *elem) {
    printf("%p %p %p\n", elem, elem->next, elem->prev); 
    printf("%d %d %d\n", elem->code, elem->next->code, elem->prev->code); 
}

int main() {
    afunc(&_errorList); // prints ==> 0x601030 0x601030 0x601030
                        //            -1 -1 -1
    return 0;
}

The same is true if I print directly from main and I cannot find a case where what you explain happens. Cannot you show your exact codes ?