Question

I have a struct:

struct myStruct {

    // there are other members as well
    float U, V, W;
}
std::vector <myStruct> myVec;
myVec.resize(num);

I want to pass only myVec[].U for all myVec’s to a function.

Answer 1

Pass a pair of iterators to the function:

struct pick_U : std::unary_function<myStruct&, float&> {
    float &operator()(myStruct &ms) const { return ms.U; }
};

your_function(
    boost::make_transform_iterator(myVec.begin(), pick_U()),
    boost::make_transform_iterator(myVec.end(), pick_U()),
    ... other args ...
};

Then your_function can iterate over the floats.