EnumDisplayDevices(NULL, devNum, &disp_device, 0)， disp_device.StateFlags == 0?

zaihua zhou 1

when i used EnumDisplayDevices funcation to enum my display device, but the returen value of this funcation is not zero and disp_device.StateFlags equal to zero. its is odd. What does it mean that the StateFlags equal to zero?

Hui Liu-MSFT 38,251 Reputation points Microsoft Vendor

2022-11-11T09:49:36.097+00:00

Hi,@zaihua zhou . Welcome Microsoft Q&A.
Could you show the complete code related to your problem? Where in your code do you get the return value disp_device.StateFlags == 0? You can view the value of StateFlags here.
zaihua zhou 1 Reputation point

2022-11-11T10:04:26.85+00:00

DISPLAY_DEVICE disp_device = {0};
disp_device.cb = sizeof(DISPLAY_DEVICE);
int devNum = 0
while(EnumDisplayDevices(NULL, devnum, &disp_device, 1)){
std::cout << disp_device.StateFlags <<std::end;
}

The output is zero，This indicates that the function execution was successful。
StateFlags equals to zero cannot be found in the link, its odd, the EnumDisplayDevices function execution was successful, but StateFlags equal to zero.
Thank you for your help！
Viorel 112.1K Reputation points

2022-11-12T19:25:49.927+00:00

Maybe zero means that the monitor is not presented as being "on", is not used to mirror drawing, does not have unavailable display modes, is not a primary device, is not removable and is not VGA compatible.