C- Structure within structure

Question

If i have these structures:

struct rec {
 int key;
 double value;
};

struct node {
 struct rec record;
 struct node *next;
};

and I have to copy the values of the fields of an item struct rec *r into an item struct node *n,

can i do this?

n->record.key = r->key;
n->record.value = r->value;

Answer 1

Yes, you can make a copy of your struct one field at a time. You can also do it in a single shot:

struct rec *r = ...;
struct node *n = ...;
n->record = *r; // Copies the content of "r" into n->record

Doing it that way has the advantage of not having to revisit the copying code each time you modify the structure of struct rec.

Answer 2

Since the rec structure contains only fields of basic types, it is perfectly valid and reasonable to do:

n->record = *r;

which in this case is equivalent to copying key and value fields separately:

n->record.key = r->key;
n->record.value = r->value;