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  1. #include <iostream>
  2. #include <sstream>
  3. using namespace std;
  4.  
  5. template <int N> struct Array : Array <N - 1>
  6. {
  7.     double x;
  8.  
  9.     template<int M> double& comp() { return Array<M>::x; }
  10.     template<int M> const double& comp() const { return Array<M>::x; }
  11.  
  12.     //Prints vector
  13.     ostream& print(ostream& out) const
  14.     {
  15.         static_cast<const Array<N-1>*>(this)->print(out);
  16.         out << ", " <<x;
  17.         return out;
  18.     }
  19.  
  20.     double& operator[] (size_t i) {
  21.     	if (i == N - 1) {
  22.         	return x;
  23.     	}
  24.     	return Array<N - 1>::operator[](i);
  25. 	}
  26.  
  27.  
  28.     //Vector in place summation, without looping
  29.     Array& operator+=(const Array& v)
  30.     {
  31.         x+=v.x;
  32.         *static_cast<Array<N-1>*>(this) += static_cast<const Array<N-1>&>(v);
  33.         return *this;
  34.     }
  35. };
  36.  
  37. template <> struct Array<1>
  38. {
  39.     double x;
  40.  
  41.     template<int M> double& comp() { return Array<M>::x; }
  42.     template<int M> const double& comp() const { return Array<M>::x; }
  43.  
  44.     //Prints vector
  45.     ostream& print(ostream& out) const
  46.     {
  47.         out << x;
  48.         return out;
  49.     }
  50.  
  51.     double& operator[](size_t i) {
  52.     	if (i != 0) { // If you don't care about strange behavior, you can remove this.
  53.         	throw std::out_of_range("Oops!");
  54.     	}
  55.     	return x; 
  56. 	}
  57.  
  58.     //Vector in place summation, without looping
  59.     Array& operator+=(const Array& v)
  60.     {
  61.         x+=v.x;
  62.         return *this;
  63.     }
  64. };
  65.  
  66. template<int N>
  67. ostream& operator<<(ostream& out, const Array<N>& v)
  68. {
  69.     out << "("; v.print(out); out << ")";
  70.     return out;
  71. }
  72.  
  73. int main() {
  74. 	Array<3> vec;
  75.  
  76. 	vec[0] = 1; vec[1] = 2; vec[2] = 3;
  77.  
  78. 	cout << vec << endl;
  79.  
  80. 	cout << (vec+=vec) << endl;
  81.  
  82. 	return 0;
  83. }
Success #stdin #stdout 0s 3468KB
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https://ideone.com/CQqgUQ
language:
C++ (gcc 8.3)
created:
7 years ago
visibility:
public

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