- Solutions

// vectorArithmeticExpressionTemplates.cpp
#include <cassert>
#include <iostream>
#include <vector>
template<typename T, typename Cont= std::vector<T> >
class MyVector{
  Cont cont;   
public:
  // MyVector with initial size
  explicit MyVector(const std::size_t n) : cont(n){}
  // MyVector with initial size and value
  MyVector(const std::size_t n, const double initialValue) : cont(n, initialValue){}
  // Constructor for underlying container
  explicit MyVector(const Cont& other) : cont(other){}
  // assignment operator for MyVector of different type
  template<typename T2, typename R2>
  MyVector& operator=(const MyVector<T2, R2>& other){
    assert(size() == other.size());
    for (std::size_t i = 0; i < cont.size(); ++i) cont[i] = other[i];
    return *this;
  }
  // size of underlying container
  std::size_t size() const{ 
    return cont.size(); 
  }
  // index operators
  T operator[](const std::size_t i) const{ 
    return cont[i]; 
  }
  T& operator[](const std::size_t i){ 
    return cont[i]; 
  }
  // returns the underlying data
  const Cont& data() const{ 
    return cont; 
  }
  Cont& data(){ 
    return cont; 
  }
};
// MyVector + MyVector
template<typename T, typename Op1 , typename Op2>
class MyVectorAdd{
  const Op1& op1;
  const Op2& op2;
public:
  MyVectorAdd(const Op1& a, const Op2& b): op1(a), op2(b){}
  T operator[](const std::size_t i) const{ 
    return op1[i] + op2[i]; 
  }
  std::size_t size() const{ 
    return op1.size(); 
  }
};
// MyVector - MyVector
template<typename T, typename Op1, typename Op2>
class MyVectorSub {
	const Op1& op1;
	const Op2& op2;
public:
	MyVectorSub(const Op1& a, const Op2& b) : op1(a), op2(b) {}
	T operator[](const std::size_t i) const {
		return op1[i] - op2[i];
	}
	std::size_t size() const {
		return op1.size();
	}
};
// elementwise MyVector * MyVector
template< typename T, typename Op1 , typename Op2 >
class MyVectorMul {
  const Op1& op1;
  const Op2& op2;
public:
  MyVectorMul(const Op1& a, const Op2& b ): op1(a), op2(b){}
  T operator[](const std::size_t i) const{ 
    return op1[i] * op2[i]; 
  }
  std::size_t size() const{ 
    return op1.size(); 
  }
};
// elementwise MyVector / MyVector
template< typename T, typename Op1, typename Op2 >
class MyVectorDiv {
	const Op1& op1;
	const Op2& op2;
public:
	MyVectorDiv(const Op1& a, const Op2& b) : op1(a), op2(b) {}
	T operator[](const std::size_t i) const {
		return op1[i] / op2[i];
	}
	std::size_t size() const {
		return op1.size();
	}
};
// function template for the + operator
template<typename T, typename R1, typename R2>
MyVector<T, MyVectorAdd<T, R1, R2> >
operator+ (const MyVector<T, R1>& a, const MyVector<T, R2>& b){
  return MyVector<T, MyVectorAdd<T, R1, R2> >(MyVectorAdd<T, R1, R2 >(a.data(), b.data()));
}
// function template for the - operator
template<typename T, typename R1, typename R2>
MyVector<T, MyVectorSub<T, R1, R2> >
operator- (const MyVector<T, R1>& a, const MyVector<T, R2>& b) {
	return MyVector<T, MyVectorSub<T, R1, R2> >(MyVectorSub<T, R1, R2 >(a.data(), b.data()));
}
// function template for the * operator
template<typename T, typename R1, typename R2>
MyVector<T, MyVectorMul< T, R1, R2> >
operator* (const MyVector<T, R1>& a, const MyVector<T, R2>& b){
  return MyVector<T, MyVectorMul<T, R1, R2> >(MyVectorMul<T, R1, R2 >(a.data(), b.data()));
}
// function template for the / operator
template<typename T, typename R1, typename R2>
MyVector<T, MyVectorDiv< T, R1, R2> >
operator/ (const MyVector<T, R1>& a, const MyVector<T, R2>& b) {
	return MyVector<T, MyVectorDiv<T, R1, R2> >(MyVectorDiv<T, R1, R2 >(a.data(), b.data()));
}
// function template for < operator
template<typename T>
std::ostream& operator<<(std::ostream& os, const MyVector<T>& cont){  
  std::cout << std::endl;
  for (int i=0; i<cont.size(); ++i) {
    os << cont[i] << ' ';
  }
  os << std::endl;
  return os;
} 
int main(){
  MyVector<double> x(10,5.4);
  MyVector<double> y(10,10.3);
  MyVector<double> result(10);
  
  result = x + x + y * y - x + x + y / y;
  
  std::cout << result << std::endl;
  
}