AMDG anony wrote:
anony wrote:
What I see in
vertices[][3] = { ... };
is an a array object of array objects. Nowhere in the standard did I ever see multidimensional arrays specifically mentioned.
It's in: 5.3.4 New section 5 (which notes: the type of new int[i][10] is int (*)[10]), and 6 8.3.4 Arrays sections 2, 3, 4, 7, and 8 8.5.1 aggregates sections 10 and 11 on array initialization, 13.1 Overloadable Declarations section 3 which notes that Parameter declarations that differ only in a pointer * versus an array [] are equivalent. That is, the array declaration is adjusted to become a pointer declaration (8.3.5) 20.5.6.4 Array modifications, Table 39.
and on and on in many more places, all consistently saying the for a multidimensional array, all but the final dimensions are pointers.
No. You have it backwards. The outermost dimension is treated as a pointer in some contexts.
Since the elements of this array are arrays, these arrays must be contiguous in memory.
What you're missing, is that it's required in the standard (8.3.4 section 6), to consider an array as a pointer to it's first element, so an array of arrays is an array of pointers (well explained in 8.3.4 section 7 and 8). For example in gcc, this code:
#include <iostream>
int main() { int array[2][2];
std::cout << std::hex << array[0] << std::endl; std::cout << array[1] << std::endl; std::cout << &array[0][0] << std::endl; std::cout << &array[1][0] << std::endl; std::cout << std::dec << sizeof(array[1]) << std::endl; std::cout << sizeof(array[1][1]) << std::endl;
}
prints out 0xbff3519c 0xbff351a4 0xbff3519c 0xbff351a4 8 4
on one particular run, showing that array[0], and array[1] are just the addresses of their first elements, their elements are 8 byte pointers to 4 byte ints. The pointers are the elements of the array, and as you pointed out, have to be contiguous. There's nothing in the standard that requires that the rows pointed to have to be contiguous, because they aren't the elements of the array, the pointers to them are.
No. What you're seeing is that an array implicitly converts to a pointer to its first element.
So, the contents of the rows have to be contiguous, and the pointers to the rows have to be contiguous, but the rows themselves don't have to be.
Yes they do. An array as the element of an array is no different from any other element type. In Christ, Steven Watanabe