`bit::matrix` — Custom Formatting

We specialize the std::formatter class to connect any bit::matrix to std::format and friends.

template<std::unsigned_integral Block, typename Allocator>
struct std::formatter<bit::matrix<Block, Allocator>> {
    ...
};

As shown in the example below, if \(M\) is a bit-matrix this std::formatter supports the four different format specifiers:

1std::format("{}",   M)
2std::format("{:p}", M)
3std::format("{:x}", M)

1: Outputs M row-by-row as bit-vectors in their default format.
2: Outputs M in a “pretty” format.
3: Outputs M row-by-row as bit-vectors in the hex format.`

Any unrecognized specifier will result in the bit-matrix string showing an error message. The sample program below has an example.

Example

#include <bit/bit.h>
int main()
{
    auto m = bit::matrix<>::random(4);
    std::cout << std::format("Matrix default specifier:\n{}\n", m);
    std::cout << std::format("Matrix pretty specifier:\n{:p}\n", m);
    std::cout << std::format("Matrix hex specifier:\n{:x}\n", m);
    std::cout << std::format("Matrix invalid specifier:\n{:X}\n", m);
}

Output

Matrix default specifier:
1010
0010
0101
1011
Matrix pretty specifier:
│1 0 1 0│
│0 0 1 0│
│0 1 0 1│
│1 0 1 1│
Matrix hex specifier:
0x5
0x4
0xA
0xD
Matrix invalid specifier:
'UNRECOGNIZED FORMAT SPECIFIER FOR BIT-MATRIX'

See Also