Screen resolutions winapi

std::vector< std::pair<int, int> > Window::displayResolutions(int display_index) const
{
    std::vector< std::pair<int, int> > display_modes;

    DEVMODE dm = { 0 };
    dm.dmSize = sizeof(dm);
    for(int iModeNum = 0; EnumDisplaySettings( NULL, iModeNum, &dm ) != 0; iModeNum++ )
    {
        display_modes.push_back( {dm.dmPelsWidth, dm.dmPelsHeight} );
    }

    sort(display_modes.begin(), display_modes.end());
    display_modes.erase(unique(display_modes.begin(), display_modes.end()), display_modes.end());

    return display_modes;
}