Question

If I had a class foo then

class foo{
   vector <int> vec;
   int someint;

   public:
   foo(number n): someint(n){}


}

How would I write a constructor for the vector, for class foo? Moreoever, I can use:

int get_someint() const{

  return someint;
}

To return an int, but what about vectors?

Answer 1

When working with complex data types, its usually best to work with references, or const-references like so:

class A
{
public:
    A()  {}  // default construct of A, v_ is empty

    A(const std::vector<int>& source)
      : v_(source)  // construct A, given a vector that is 
                    // copied into v_
    {
    }

    // returns an immutable reference to v_
    const std::vector<int>& get_v() const
    {
       return v_;
    }

    // returns a mutable reference to v_
    std::vector<int>& get_v()
    {
        return v_;
    }
private:
    std::vector<int> v_;
};

Example usage:

A a_no_vec;  // A has an empty vector v_

std::vector<int> src;

src.push_back(16);
src.push_back(19);

A a_with_vec(src);  // A has a vector that is a copy of src