OpenCV in C++: "Unknown Type Name" - c++

Question

I'm trying to follow along with the OpenCV tutorial, found here. Part of the tutorial is to create a SURF feature detector.
Unlike the tutorial, my code is in a header file, like this:
class Img {
Mat mat;
int minHessian = 400;
SurfFeatureDetector detector(minHessian);
public:
...
}
The error I'm getting occurs on the line
SurfFeatureDetector detector(minHessian);
and the error is:
Unknown type name 'minHessian'
When I do not put this in a separate class, the compiler does not complain. I have also checked and I have imported the required libraries.
Can anybody tell me what the error is, and how to fix it?

Answer 1

I read the opencv tutorial code:
Mat img1 = imread(argv[1], CV_LOAD_IMAGE_GRAYSCALE);
Mat img2 = imread(argv[2], CV_LOAD_IMAGE_GRAYSCALE);
if(img1.empty() || img2.empty())
{
printf("Can't read one of the images\n");
return -1;
}
// detecting keypoints
SurfFeatureDetector detector(400);
vector<KeyPoint> keypoints1, keypoints2;
detector.detect(img1, keypoints1);
detector.detect(img2, keypoints2);
....
ans as I understand, in this code, the SurfFeatureDetector detector(minHessian); is not a signature of a function that you can write in your header file as you did; but it's actually calling the SurfFeatureDetector function in the code.
So, I think if you remove it from your header file code, and put it in your function(s), where you want call it, it may work.