std::array<T,N>:: fill

#include <array>
#include <cstddef>
#include <iostream>
int main()
{
    constexpr std::size_t xy = 4;
    using Cell = std::array<unsigned char, 8>;
    std::array<Cell, xy * xy> board;
    board.fill({0xE2, 0x96, 0x84, 0xE2, 0x96, 0x80, 0, 0}); // "▄▀";
    for (std::size_t count{}; Cell c : board)
        std::cout << c.data() << ((++count % xy) ? "" : "\n");
}