2. I’ll write some test code on setting names, but what you’re proposing is very close to one good way to do it.

3. I think this is overkill. These are public fields, so p->artist_name is just fine but it really depends on whether you want your strings on the stack or on the heap. What I’ve shown here expects an allocated char buffer, hence the calls to free. Also, the code above may or may not complain about unallocated memory, I’m going to revise it slightly to mitigate that.

If you wanted to make them private fields, use char * get_artist_name(Painting * p) to send back a copy. However, I’m going to think about this and write up some test code to see how it behaves, and figure out what a viable use case would be.

Thanks for your observations. I code very little C these days, but it’s still one of my favorite languages.

1:
Ok, so you wouldn’t actually include it in the set function because then the user might not see the malloc and thus forget to free it?

2:
You said you guard against possible buffer overflows, would it be unsafe if I do it like this:

void painting_set_artist_name(Painting * p, char * artist_name) {
size_t s = strlen(artist_name)+1; // check inside the function
strncpy(p->artist_name, artist_name, s);
p->artist_name[s] = ”;
}

painting_set_artist_name(p, “Picasso”);

3:
Basically, I wanted to know what you think about the technique to include a function pointer as is done in the struct below:

struct painting {
uint32_t inventory_control;
uint32_t purchase_price;
char * painting_name;
char * artist_name;
char * owner_name;
char * (*get_artist_name)(Painting *);
void (*set_artist_name)(Painting *, char *);
};

// this could also be done in a separate setup function when creating the object
p->set_artist_name = &painting_set_artist_name;

// this would be our call in the code
p->set_artist_name(p, “Picasso”);

1. “how to allocate memory for the pointer fields.”

   This is a great question. The answer partly depends on how you’re using the object. For the char * in this struct, I’m assuming that the using code will allocate somewhere along the way, and – this is important – these pointers aren’t referenced by any other code.

2. “why you passed the character length in a separate parameter instead of determining it directly in the function itself?”

   Not sure exactly what you mean. Which line of which snippet?

3. “What do you think of using function pointers in the struct itself to access the fields?”

   Not exactly sure what you mean, please post a little snippet. Also, read the articles on single inheritance in c, that might asnwer your question.

David M. Doolin, PhD´s last [type] ..Why Free Software costs so little… and costs so much

Therefore the essay can be found in a few seconds, if you have the original URL (and you did):
http://web.archive.org/web/20070630120840/http://www.dekorte.com/docs/essays/ooc/