multi_vector

multi_vector.h

template <typename T, int dim> class multi_vector_tool;
template <typename T, int dim> using multi_vector = typename multi_vector_tool<T,dim>::type;
template <typename T, int dim>
struct multi_vector_tool{
  typedef std::vector<typename multi_vector_tool<T,(dim-1)>::type> type;
  static void resize( multi_vector<T,dim> & vec, std::array<int,dim> index, T v = T{} ){
    vec.resize( index[0] );
    std::array<int,dim-1> index2;
    std::copy(index.begin()+1,index.end(), index2.begin() );
    for( auto & a : vec )
      multi_vector_tool<T,dim-1>::resize( a, index2, v );
  }
};
template <typename T>
struct multi_vector_tool<T,0>{
  typedef T type;
  static void resize( multi_vector<T,0> & vec, std::array<int,0> index, T v = T{}){
    vec = v ;
  }
};

test_multi_vector.cxx

#include <iostream>
#include "multi_vector.h"
useing namespace std;

int main(){
  multi_vector<int,2> a1;
  multi_vector_tool<int,2>::resize( a1, { 2, 3 } );
  
  cout<<"a1 : "<<a1.size()<<endl;
  for( auto a2 : a1 ){
    cout<<"a2 : "<<a2.size()<<endl;
    for( auto a3 : a2) {
      cout<<a3<<endl;
    }
  }
  
  return 0;
}