Question

I need to create a structure that allows me to define an x number of points (the number of points changes at run time) in a 3-D coordinate system. Each point has an x, y, and z value. So far I have a basic structure like this, but I need it to be able to have multiple points, each with their own values.

struct point {
        int point_num;
        double x;
        double y;
        double z;
};

Thanks!

Answer 1

If point_num is a non-contiguous but unique identifier you could use std::map<int, point> and remove the identifier from the struct. That way you get O(log(N)) lookup using the index.

If point_num values are unique and contiguous, use std::vector<point> – again the id field is superfluous, as the location in the vector provides an indexing value for you.

Read up a bit on STL, especially containers, before you go much further.