// simple_vector.h: simple vectors - probably wouldn't want to use in real code
// based on Stroustrup, A Tour of C++ (2014), p. 37

#include <stdexcept>

class AbstractContainer {
public:
  virtual double& operator[](int index) = 0;
  virtual int size() = 0;
  virtual ~AbstractContainer() { }
};  

class FixedVector : public AbstractContainer {
public:
  FixedVector(int size) : elements{new double[size]}, _size{size}
  {
    for(int i = 0; i < size; ++i)
      elements[i] = 0.0;
  }
   
 ~FixedVector() {
    delete [] elements;
  }

  int size() override { return _size; }

  double& operator[](int index) override {
    if ( index < 0 || index >= _size )
      throw std::out_of_range("Illegal index into vector.");
    return elements[index];
  }
private:
  int _size;                   // debugging trick: put first for visibility
  double *elements;
};