Pointers

Pointers contain an address of a value of the given type. A &T is a pointer to value of type T. If a pointer is not pointing to anything, its value is null.

Use the & operator to take the address of a value. Note the consistency between the type and operation used to create a pointer.

x: i32  = 10;
p: &i32 = &x;

Use the * operator to retrieve the value out of a pointer. This is not a safe operation, so faults can occur if the pointer is pointing to invalid memory.

x := 10;
p := &x;

printf("*p is {}.\n", *p);

Multi-pointers

Normal pointers in Onyx do not support pointer addition nor subscripting, i.e. x[i]. To do this, a multi-pointer must be used.

Multi-pointers are written as [&] T. They implicitly convert to-and-from normal pointer types, so they do not add much to the safely of a program, but they do allow for expressed intent when using pointers. Consider these two procedures; there is a clear difference between how the pointers are going to be used.

proc_1 :: (out: &i32) {
    *out = 10;
}

proc_2 :: (out: [&] i32) {
    for 10 {
        out[it] = it;
    }
}

Note, pointer addition and substraction on [&] T steps with sizeof(T).

So, cast([&] i32, 0) + 1 == 4.

Pointers vs Multi-Pointers