CODEWITHSUNDEEP
csyntax
pen
pen

Reputation: 33

Static initialization of a struct with pointer to other, as-yet undeclared static variable

C syntax question.

I am looking to make a declaration something like the following:

struct thingy {
    struct thingy* pointer;
}

static struct thingy thing1 = {
    .pointer = &thing2
};

static struct thingy thing2 = {
    .pointer = &thing1
};

I have tried declaring and initializing separately, as in:

struct thingy {
    struct thingy* pointer;
}

static struct thingy thing1;
static struct thingy thing2;

thing1 = {
    .pointer = &thing2
};

thing2 = {
    .pointer = &thing1
};

However I am not sure whether I can declare and initialize static variables separately

Is there a way I can actually get these to point to each other from compilation?

Upvotes: 3

Views: 1041

Answers (1)

jxh
jxh

Reputation: 70502

You were almost there. You need to "forward declare" (actually, this is a tentative definition, thanks AndreyT!) the static instances first, and then initialize their definitions with the desired pointers.

static struct thingy thing1;
static struct thingy thing2;

static struct thingy thing1 = {
    .pointer = &thing2
};

static struct thingy thing2 = {
    .pointer = &thing1
};

Technically, you only need to forward declare tentatively define thing2.

Upvotes: 3

Related Questions