trying to disable VIDEOIO ERROR message

edit

I'm making a sample function to detect whether the webcam is plugged in the USB or not like:

VideoCapture video(-1);
Mat frame;
video>>frame;
if( frame.cols>0)
{
    cout<<"camera's back!"<<endl;
}

It's all work fine but it would output the following message if no camera here

VIDEOIO ERROR: V4L: can't find camera device

I don't want to show the opencv error message in my own program so I write this:

int handleError( int status, const char* func_name,
            const char* err_msg, const char* file_name,
            int line, void* userdata )
{
    return 0; 
}

and put the

cv::redirectError(handleError);

before the VideoCapture but noting happened. I also tried cvSetErrMode(2) (not good but I cannot find the current version of this function) and still, nothing happened.

How do I disable the VIDEOIO ERROR message?