Adjust brightness the native way in Windows

I was wondering what is the native way to adjust the brightness in Windows?

By native, I mean the method that also displays the brightness overlay in the top left corner in Windows 8, 8.1, and 10, as if the special brightness keys have been pressed.

I was looking all over the Internet for this, but some solutions that do work, adjust the brightness, but no overlay is shown. Any idea? Is there something like

SendMessage(HWND_BROADCAST, WM_SYSCOMMAND, SC_MONITORPOWER, 2);

which turns off the monitor, but for brightness, that can be used from C++? Or C#? Thanks.

Update: here is the sample code.

HMONITOR hMonitor = NULL;
DWORD cPhysicalMonitors;
LPPHYSICAL_MONITOR pPhysicalMonitors = NULL;

// Get the monitor handle.
hMonitor = MonitorFromWindow(GetForegroundWindow(), MONITOR_DEFAULTTOPRIMARY);

// Get the number of physical monitors.
BOOL bSuccess = GetNumberOfPhysicalMonitorsFromHMONITOR(
    hMonitor,
    &cPhysicalMonitors
);

if (bSuccess)
{
    // Allocate the array of PHYSICAL_MONITOR structures.
    pPhysicalMonitors = (LPPHYSICAL_MONITOR)malloc(
        cPhysicalMonitors * sizeof(PHYSICAL_MONITOR));

    if (pPhysicalMonitors != NULL)
    {
        // Get the array.
        bSuccess = GetPhysicalMonitorsFromHMONITOR(
            hMonitor, cPhysicalMonitors, pPhysicalMonitors);

        // Use the monitor handles (not shown).
        DWORD pdwMinimumBrightness = 0;
        DWORD pdwCurrentBrightness = 0;
        DWORD pdwMaximumBrightness = 0;

        DWORD dwMonitorCapabilities = 0;
        DWORD dwSupportedColorTemperatures = 0;

        bSuccess = GetMonitorCapabilities(pPhysicalMonitors, &dwMonitorCapabilities, &dwSupportedColorTemperatures);

        cout << bSuccess << endl;

        // Close the monitor handles.
        bSuccess = DestroyPhysicalMonitors(
            cPhysicalMonitors,
            pPhysicalMonitors);

        // Free the array.
        free(pPhysicalMonitors);
    }
}

cout << bSuccess always writes 0 in terminal.

GetMonitorCapabilities fails with error -1071241854 (0xC0262582: "An error occurred while transmitting data to the device on the I2C bus."). Then how do the brightness keys on my computer work?