Get Windows monitors names. Control monitor brightness via DirectX API. https://social.msdn.microsoft.com/Forums/en-US/668e3cf9-4e00-4b40-a6f8-c7d2fc1afd39/how-can-i-retrieve-monitor-information?forum=windowsgeneraldevelopmentissues#be6e67f3-c2a7-4647-bb39-ed4fbec5dce4

brightness_ctl_DDC.cpp

// Phys monitor control via DDC/CI or VESA commands
// (David Lowndes)
// From https://social.msdn.microsoft.com/Forums/en-US/5437ddb8-af86-4cf0-8061-798e6601e08e/how-to-control-system-brightness-using-windows-api-?forum=windowsgeneraldevelopmentissues#554b7b7f-0aab-429d-9c36-fd39608979b0

#include <Windows.h>
#include <physicalmonitorenumerationapi.h>
#include <highlevelmonitorconfigurationapi.h>
#pragma comment( lib, "Dxva2.lib" )

void 
test_brightness()
{

	HWND win_handle = GetDesktopWindow();
	HMONITOR hMon = MonitorFromWindow(win_handle, MONITOR_DEFAULTTOPRIMARY);

	if (hMon != NULL)
	{
		DWORD num_of_monitors;
		BOOL bOK = GetNumberOfPhysicalMonitorsFromHMONITOR(hMon, &num_of_monitors);
		if (bOK)
		{
			LPPHYSICAL_MONITOR pPhysical_monitors = (LPPHYSICAL_MONITOR)malloc(num_of_monitors * sizeof(
				PHYSICAL_MONITOR));
			if (pPhysical_monitors != NULL)
			{
				bOK = GetPhysicalMonitorsFromHMONITOR(hMon, num_of_monitors, pPhysical_monitors);
			}

			HANDLE hMonitor = pPhysical_monitors[0].hPhysicalMonitor;

			DWORD min, cur, max;
			bOK = GetMonitorBrightness(hMonitor, &min, &cur, &max);
			if (!bOK)
			{
				DWORD Err = GetLastError();
				Err = Err;
			}
			else
			{
				// Check altering the brightness
				bOK = SetMonitorBrightness(hMonitor, cur / 32);

				if (bOK)
				{
					bOK = SetMonitorBrightness(hMonitor, cur);
				}
			}
		}
	}
}

test-monitors.cpp

// test-monitors.cpp
// https://social.msdn.microsoft.com/Forums/en-US/668e3cf9-4e00-4b40-a6f8-c7d2fc1afd39/how-can-i-retrieve-monitor-information?forum=windowsgeneraldevelopmentissues#be6e67f3-c2a7-4647-bb39-ed4fbec5dce4

#include <Windows.h>
#include <iostream>
#include <vector>
#include <cstdio>

std::wstring getMonitorName(HMONITOR monitor) {
    MONITORINFOEXW info;
    info.cbSize = sizeof(info);
    GetMonitorInfoW(monitor, &info);

    UINT32 requiredPaths, requiredModes;
    GetDisplayConfigBufferSizes(QDC_ONLY_ACTIVE_PATHS, &requiredPaths, &requiredModes);
    std::vector<DISPLAYCONFIG_PATH_INFO> paths(requiredPaths);
    std::vector<DISPLAYCONFIG_MODE_INFO> modes(requiredModes);
    QueryDisplayConfig(QDC_ONLY_ACTIVE_PATHS, &requiredPaths, paths.data(), &requiredModes, modes.data(), nullptr);

    for (auto& p : paths) {
        DISPLAYCONFIG_SOURCE_DEVICE_NAME sourceName;
        sourceName.header.type = DISPLAYCONFIG_DEVICE_INFO_GET_SOURCE_NAME;
        sourceName.header.size = sizeof(sourceName);
        sourceName.header.adapterId = p.sourceInfo.adapterId;
        sourceName.header.id = p.sourceInfo.id;
        DisplayConfigGetDeviceInfo(&sourceName.header);
        if (wcscmp(info.szDevice, sourceName.viewGdiDeviceName) == 0) {
            DISPLAYCONFIG_TARGET_DEVICE_NAME name;
            name.header.type = DISPLAYCONFIG_DEVICE_INFO_GET_TARGET_NAME;
            name.header.size = sizeof(name);
            name.header.adapterId = p.sourceInfo.adapterId;
            name.header.id = p.targetInfo.id;
            DisplayConfigGetDeviceInfo(&name.header);
            return std::wstring(name.monitorFriendlyDeviceName);
        }
    }
    return L"";
}


BOOL CALLBACK MyInfoEnumProc(
    HMONITOR hMonitor,
    HDC hdcMonitor,
    LPRECT lprcMonitor,
    LPARAM dwData
)
{
    MONITORINFOEX mi;
    ZeroMemory(&mi, sizeof(mi));
    mi.cbSize = sizeof(mi);
    GetMonitorInfo(hMonitor, &mi);
    wprintf(L"DisplayDevice: %s\n", mi.szDevice);

    std::wcout << L"Name: " << getMonitorName(hMonitor) << L"\n";
    return TRUE;
}

int main()
{
    printf("\n\nEnumDisplayDevices\n\n\n");

    DISPLAY_DEVICE dd;
    ZeroMemory(&dd, sizeof(dd));
    dd.cb = sizeof(dd);
    for (int i = 0; EnumDisplayDevices(NULL, i, &dd, 0); i++)
    {
        wprintf(L"\n\nDevice %d:", i);
        wprintf(L"\n    DeviceName:   '%s'", dd.DeviceName);
        wprintf(L"\n    DeviceString: '%s'", dd.DeviceString);
        wprintf(L"\n    StateFlags:   %s%s%s%s%s",
            ((dd.StateFlags &
                DISPLAY_DEVICE_ATTACHED_TO_DESKTOP) ?
                L"desktop " : L""),
            ((dd.StateFlags &
                DISPLAY_DEVICE_PRIMARY_DEVICE) ?
                L"primary " : L""),
            ((dd.StateFlags & DISPLAY_DEVICE_VGA_COMPATIBLE) ?
                L"vga " : L""),
            ((dd.StateFlags &
                DISPLAY_DEVICE_MULTI_DRIVER) ?
                L"multi " : L""),
            ((dd.StateFlags &
                DISPLAY_DEVICE_MIRRORING_DRIVER) ?
                L"mirror " : L""));

        // Get more info about the device
        DISPLAY_DEVICE dd2;
        ZeroMemory(&dd2, sizeof(dd2));
        dd2.cb = sizeof(dd2);
        EnumDisplayDevices(dd.DeviceName, 0, &dd2, 0);
        wprintf(L"\n    DeviceID: '%s'", dd2.DeviceID);
        wprintf(L"\n    Monitor Name: '%s'", dd2.DeviceString);
    }

    printf("\n\n\nEnumDisplayMonitors\n\n\n");

    EnumDisplayMonitors(NULL, NULL, MyInfoEnumProc, 0);


    return 0;
}