#include <cassert>
#include <cstddef>
#include <cstdio>

class Vector
{
    public:
        Vector(std::size_t dim);
        ~Vector();

        double &operator()(std::size_t index);
        double operator()(std::size_t index) const;

        double *data;
        std::size_t dim;
};

Vector::Vector(std::size_t dim)
    : data(new double[dim]), dim(dim)
{
}

Vector::~Vector()
{
    delete [] data;
}

double &
Vector::operator()(std::size_t index)
{
    assert(index < dim);
    return data[index];
}

double
Vector::operator()(std::size_t index) const
{
    assert(index < dim);
    return data[index];
}

void
print(const Vector &x)
{
    for (size_t i = 0; i < x.dim; ++i) {
        std::printf("%lf", x(i));
        if (i + 1 < x.dim) {
            std::printf(", ");
        }
    }
}

int
main(void)
{
    Vector x(4);

    for (std::size_t i = 0; i < x.dim; ++i) {
        x(i) = 42 + i;
    }

    print(x);
    printf("\n");
}