printing elements of a vector<Point2i>

Question

If I have a vector and I initialize it like this. How do I access just the first part of the point separately and second separately.

vector<Point2i> cent_i(1); // how do i initialize with a point like (1,2 )
cent_i[0][0] = (floor( s.width/2)); //TRYING TO change the points
cent_i[0][1] = (floor( s.height/2));

I don't know if I am doing this right

Answer 1

Based on the Documentation from OpenCv. Here is how you index a std::vector of Point2i named points :

points[0].x, points[0].y, points[1].x, points[1].y, ...

Answer 2

You can initialize the point directly in the constructor, like:

vector<Point> pts {Point(1,2), Point(3,4), Point(5,6)};

or:

vector<Point> pts {{1,2}, {3,4}, {5,6}};

You can access i-th Point of the vector like:

pts[i].x = ...
pts[i].y = ...

Remember that Point is just a typedef for Point2i .