I’m using raspberry PI 4, and I want to set my line to use the internal PULL_UP (default Raspberry lines above 8 are all pull_down):

Using C++ and libgpiod:

try
{
    gpiod::chip chip("gpiochip0");
    gpiod::line_bulk lines;

    const std::vector<io_gpio_t> offsets = {
        {1, 21},
        {2, 26},
        {3, 16},
        {4, 19}};

    for (io_gpio_t offset : offsets)
    {
        auto line = chip.get_line(offset.gpio_line);
        line.set_bias(gpiod::line::bias::pull_up); <<---- ERROR HERE!!!!
        line.request({"io", gpiod::line_request::EVENT_BOTH_EDGES, 100000});
        lines.append(line);
    }

    while (true)
    {
        gpiod::line_bulk changed_lines = lines.event_wait(std::chrono::seconds(10));
        for (gpiod::line line : changed_lines)
        {
            auto event = line.event_read();
            int offset = line.offset();
            process_digital_in(offset, event); // Process event
        }
    }
}
catch (const std::exception &e)
{
    std::cerr << "Error: " << e.what() << std::endl;
}

}

Seens that version 1.6 of libgpiod does not support set_bias:

src/IO.cpp:79:18: error: ‘class gpiod::line’ has no member named ‘set_bias’; did you mean ‘set_flags’?
   79 |             line.set_bias(gpiod::line::bias::pull_up);
      |                  ^~~~~~~~
      |                  set_flags
src/IO.cpp:79:40: error: ‘gpiod::line::bias’ is not a class, namespace, or enumeration
   79 |             line.set_bias(gpiod::line::bias::pull_up);
      |                                        ^~~~

Compiler suggests set_flags, but I cannot find docs on that.

How to properly set the input to use the internal pull up programatically?