`bit::vector` — Some Special Bit-Vectors

Class methods to construct some special bit-vectors:

1static constexpr bit::vector zeros(std::size_t n);
2static constexpr bit::vector ones(std::size_t n);
3static constexpr bit::vector unit(std::size_t n, std::size_t i);
4static constexpr bit::vector checker_board(std::size_t n, int first = 1);

1: Returns a bit-vector of size n where all the elements are set to 0.
2: Returns a bit-vector of size n where all the elements are set to §.
3: Returns the i’th unit bit-vector of size n.
4: Returns a bit-vector of size n with a pattern that 1010101... or 0101010...

The \(i^\mathrm{th}\) unit bit-vector of size \(n\) is all zeros apart from the i’th element, which is 1.

The method unit(n, i) requires \(i < n\). This condition is always checked unless the NDEBUG flag is set, as it generally is for release builds.

Example

#include <bit/bit.h>
int main()
{
    std::size_t n = 16;

    auto v0 = bit::vector<>::zeros(n);
    auto v1 = bit::vector<>::ones(n);
    auto v2 = bit::vector<>::checker_board(n, 1);
    auto v3 = bit::vector<>::checker_board(n, 0);
    std::cout << "All zeros:              " << v0 << "\n";
    std::cout << "All ones:               " << v1 << "\n";
    std::cout << "Checker-board from 1:\t" << v2 << "\n";
    std::cout << "Checker-board from 0:\t" << v3 << "\n";
    // The unit vectors
    for(std::size_t i = 0; i < n; ++i)
    {
        auto u = bit::vector<>::unit(n, i);
        std::cout << "Unit bit-vector " << i << ":\t" << u << "\n";
    }
}

Output

All zeros:              [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]
All ones:               [1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1]
Checker-board from 1:   [1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0]
Checker-board from 0:   [0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1]
Unit bit-vector 0:      [1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]
Unit bit-vector 1:      [0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0]
Unit bit-vector 2:      [0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0]
Unit bit-vector 3:      [0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0]
Unit bit-vector 4:      [0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0]
Unit bit-vector 5:      [0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0]
Unit bit-vector 6:      [0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0]
Unit bit-vector 7:      [0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0]
Unit bit-vector 8:      [0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0]
Unit bit-vector 9:      [0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0]
Unit bit-vector 10:     [0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0]
Unit bit-vector 11:     [0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0]
Unit bit-vector 12:     [0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0]
Unit bit-vector 13:     [0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0]
Unit bit-vector 14:     [0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0]
Unit bit-vector 15:     [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1]

See Also