Ciclic dependency problem

main.cpp

//File main.cpp --------------------------
#include "main.h"
#include "int_vector.h"

//We're not using accumulate because our
//int_vector example doesn't support.
int get_total(const int_vector &v) {
  int total = 0;
  for(int i=0; i < v.size(); i++) {
    total += v[i];
  }
  return total;
}

//File main.h ----------------------------
int get_total(std::vector<int> &v);

//File int_vector.h ----------------------
struct int_vector {
  //implementation details ...
  int size() { return _size; }
  int operator[](int pos) { 
    return _data[pos];
  }
  int *_data;
};