Method within_1ulp

test/stream_parser.cpp:612–630

    };

    bool
    within_1ulp(double x, double y)
    {
        std::uint64_t bx, by;
        std::memcpy(&bx, &x, sizeof(x));
        std::memcpy(&by, &y, sizeof(y));

        auto diff = bx - by;
        switch (diff)
        {
        case 0:
        case 1:
        case 0xffffffffffffffff:
            return true;
        default:
            break;
        }
        return false;
    }

    // Verify that f converts to the
    // same double produced by `strtod`.