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  1. #include <iostream>
  2. #include <sstream>
  3. #include <vector>
  4. using namespace std;
  5.  
  6. template <int N> struct Array : Array <N - 1>
  7. {
  8.     double x;
  9.  
  10.     Array()
  11.     {
  12.     	if (Array<N-1>::jump_table.size() < N) 
  13.     		Array<N-1>::jump_table.push_back( (char*)(&x) - (char*)(this) );
  14.     }
  15.  
  16.     template<int M> double& comp() { return Array<M>::x; }
  17.     template<int M> const double& comp() const { return Array<M>::x; }
  18.  
  19.     //Prints vector
  20.     ostream& print(ostream& out) const
  21.     {
  22.         static_cast<const Array<N-1>*>(this)->print(out);
  23.         out << ", " <<x;
  24.         return out;
  25.     }
  26.  
  27.     //Vector in place summation, without looping
  28.     Array& operator+=(const Array& v)
  29.     {
  30.         x+=v.x;
  31.         *static_cast<Array<N-1>*>(this) += static_cast<const Array<N-1>&>(v);
  32.         return *this;
  33.     }
  34. };
  35.  
  36. template <> struct Array<1>
  37. {
  38. 	//Just do your own jump table
  39. 	static std::vector<size_t> jump_table;
  40.  
  41. 	Array()
  42. 	{
  43. 		if (jump_table.size() < 1) jump_table.push_back( (char*)(&x) - (char*)(this) );
  44. 	}
  45.  
  46.     double x;
  47.  
  48.     template<int M> double& comp() { return Array<M>::x; }
  49.     template<int M> const double& comp() const { return Array<M>::x; }
  50.  
  51.     //Prints vector
  52.     ostream& print(ostream& out) const
  53.     {
  54.         out << x;
  55.         return out;
  56.     }
  57.  
  58.     double& operator[](size_t i) {
  59.     	return *(double*)((char*)(this) + jump_table[i]);
  60. 	}
  61.  
  62.     //Vector in place summation, without looping
  63.     Array& operator+=(const Array& v)
  64.     {
  65.         x+=v.x;
  66.         return *this;
  67.     }
  68. };
  69.  
  70. std::vector<std::size_t> Array<1>::jump_table;
  71.  
  72. template<int N>
  73. ostream& operator<<(ostream& out, const Array<N>& v)
  74. {
  75.     out << "("; v.print(out); out << ")";
  76.     return out;
  77. }
  78.  
  79. int main() {
  80. 	Array<3> vec;
  81.  
  82. 	vec[0] = 1; vec[1] = 2; vec[2] = 3;
  83.  
  84. 	cout << vec << endl;
  85.  
  86. 	cout << (vec+=vec) << endl;
  87.  
  88. 	return 0;
  89. }
Success #stdin #stdout 0s 3468KB
comments (?)
stdin 
Standard input is empty
stdout 
(1, 2, 3)
(2, 4, 6)
https://ideone.com/4hVIiZ
language:
C++ (gcc 8.3)
created:
9 years ago
visibility:
public

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