when i use "=" copy a object ,why source value and destination value are different? : i  am copy a object ,but source value and destination value are different ,i am not sure what happened.temp_mode not same as default_mode after copy,[details as attachemnt][1]

    bool display_device_info::change_resolution(int width,int height)
    {
    	DEVMODE temp_mode;
    	temp_mode.dmSize = sizeof(DEVMODE);
    	temp_mode.dmDriverExtra = 0;
    
    	temp_mode=default_mode;
    
    	temp_mode.dmPelsWidth = width;
    	temp_mode.dmPelsHeight = height;
    	bool res=ChangeDisplaySettings(&temp_mode, 0);
    	return res;
    }


  [1]: https://i.stack.imgur.com/VQo9J.png