Undefined identifier "CV_WINDOW_NORMAL", opencv3.*-4.*

opencv3.-4.

cv::nameWindow(“Heaven And Earth Correct”,CV_WINDOW_NORMAL | CV_WINDOW_KEEPRATIO);

Undefined identifier 'CV_WINDOW_NORMAL'

Undefined identifier 'CV_WINDOW_KEEPRATIO'

solution:

Add the header file #include <opencv2/highgui/highgui_c.h> at the beginning of the code