CODEWITHSUNDEEP
objective-cioscarraysstruct
yoninja
yoninja

Reputation: 1962

Struct array in struct [Objective-c]

Let say I have these:

typedef id Title;

typedef struct{
    Title title;
    int pages;
}Book;

So far, the code is okay. But the problem is here:

typedef struct{
   int shelfNumber;
   Book book;   //How can I make this an array of Book?
}Shelf;

Like what I have stated in the comment in the code, I want to make Book as array so that it can hold a number of books. Is that even possible? If it is, how can I do it?

Upvotes: 0

Views: 2053

Answers (2)

mpu
mpu

Reputation: 433

Note that you could use a flexible array member to achieve this effect:

typedef struct {
    int shelfNumber;
    size_t nbooks;
    Book book[];
} Shelf;

This is an elegant use case because you have the simplicity of use of a static array but if you need to allocate a Shelf object of size sz, you only have to do one malloc:

Shelf *mkShelf(int num, size_t sz) {
    Shelf *s = malloc(sizeof(Shelf) + sz * sizeof(Book));
    if (!s) return NULL;
    *s = (Shelf){ num, sz };
    return s;
}

Compound literals and flexible array members that I used above are C99 features, so if you program with VC++ it might not be available.

Upvotes: 0

ouah
ouah

Reputation: 145829

typedef struct{
    int shelfNumber;
    Book book[10];   // Fixed number of book: 10
 }Shelf;

or

typedef struct{
    int shelfNumber;
    Book *book;     // Variable number of book
 }Shelf;

in the latter case you'll have to use malloc to allocate the array.

Upvotes: 1

Related Questions