classes.cpp

double sqrt(double);    // the square root function takes a double

class Vector {
  public:
    Vector(int s);
    double& operator[](int i);
    int size();

  private:
    double* elem; // elem points to an array of sz doubles
    int sz;
};

Vector::Vector(int s) : elem {new double[s]}, sz{s}
{}

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