Is this normal behavior for a std::vector?

Question

I have a std::vector of a class called OGLSHAPE.

each shape has a vector of SHAPECONTOUR struct which has a vector of float and a vector of vector of double. it also

Answer 1

Calling std::vector<>::clear() does not necessarily free all allocated memory (it depends on the implementation of the std::vector<>). This is often done for the purpose of optimization to avoid unnessecary memory allocations.

In order to really free the memory held by an instance just do:

template 
inline void really_free_all_memory(std::vector& to_clear)
{
    std::vector v;
    v.swap(to_clear);
}

// ...
std::vector objs;

// ...
// really free instance 'objs'
really_free_all_memory(objs);

which creates a new (empty) instance and swaps it with your vector instance you would like to clear.