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  1. #include<vector>
  2. #include<iostream>
  3. using std::size_t;
  4. using std::cout;
  5.  
  6. // Creating a multidimensional container (e.g. `vector`, `map`)
  7. template<template<typename...> class Container,
  8.          typename T,  
  9.          size_t DIMENSION>
  10. struct MultiDimensional
  11. {
  12.   using internal = MultiDimensional<Container, T, DIMENSION-1>;
  13.   using type = Container<typename internal::type>;
  14.  
  15.   template<typename... Args>
  16.   static
  17.   type Generate (const size_t size, Args... sizes)
  18.   {
  19.     return type(size, internal::Generate(sizes...));
  20.   }
  21. };
  22.  
  23. // Last dimension overload
  24. template<template<typename...> class Container,
  25.          typename T>
  26. struct MultiDimensional<Container, T, 1>  
  27. {
  28.   using internal = T;
  29.   using type = Container<T>;
  30.  
  31.   static
  32.   type Generate (const size_t size)
  33.   {
  34.     return type(size);
  35.   }
  36. };
  37.  
  38. // Wrapper for the specific requirement of creating a multidimensional `std::vector`
  39. template<typename T,
  40.          typename... Args>
  41. auto make_vector(Args... sizes)
  42.  -> typename MultiDimensional<std::vector, T, sizeof...(sizes)>::type
  43. {
  44.   return MultiDimensional<std::vector, T, sizeof...(sizes)>::Generate(sizes...);
  45. }
  46.  
  47. int main ()
  48. {
  49.   size_t n = 5;
  50.   auto v3 = make_vector<int>(n+1, n*2, n*3);
  51.   cout << "v3.size() = " << v3.size() << "\n";
  52.   cout << "v3.back().size() = " << v3.back().size() << "\n";
  53.   cout << "v3.back().back().size() = " << v3.back().back().size() << "\n";
  54. }
  55.  
Success #stdin #stdout 0s 3232KB
comments (?)
stdin
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Standard input is empty
stdout
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v3.size() = 6
v3.back().size() = 10
v3.back().back().size() = 15
https://ideone.com/p2XEM8
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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