Question

I have the following problem:

“list.c”

struct nmlist_element_s {
    void *data;
    struct nmlist_element_s *next;
};

struct nmlist_s {
    nmlist_element *head;
    nmlist_element *tail;
    unsigned int size;
    void (*destructor)(void *data);
    int (*match)(const void *e1, const void *e2);
};

/*** Other code ***/

What will be the signature for a function that returns ‘destructor‘ from the structure ?
For example the signature of the function that returns ‘size‘ is:

unsigned int nmlist_size(nmlist *list);

What will be the case for ‘destructor‘ .

Answer 1

General form:

void (*get_destructor())(void *data);

Exact form will depend on what parameters get_destructor is supposed to take. If you’re just returning the destructor pointer from an instance of struct nmlist_s, then it will look like

void (*get_destructor(struct nmlist_s list))(void *data);