C++ - dynamic pointer of array

Question

first i would like to say i am Newbie in C++.

As part of my master thesis i am writing a program in C++ which also get as parameters the variables m and d (both integers). Were d is the power of 2 (this means 2^d elements). Parameter m define the number of possible interactions between one element and the total group ( 2^d elements).

The number of possible interactions is computed as following:

\kappa = \sum_{i=0}^m\binom{d}{i}

(at present i generate vector of vectors for 2^d x \\kappa, but my Prof. would like me to create different statistics to different m 's. My first though was to to generate a dynamic array of m arrays of different sizes... Then i though of defining a 3-dim array with the biggest needed 2d array, but also program speed is important (eg d = 20 ).

i would like to ask for your advice how to define such kind of dynamic array that will also be fast.

Regards

Answer 1

Use boost mutlidimensional arrays

http://www.boost.org/doc/libs/1_41_0/libs/multi_array/doc/index.html

for example look at this code. This is very easy

#include "boost/multi_array.hpp"
#include <cassert>

int main () {
  // Create a 3D array that is 3 x 4 x 2
  typedef boost::multi_array<double, 3> array_type;
  typedef array_type::index index;
  array_type A(boost::extents[3][4][2]);

  // Assign values to the elements
  int values = 0;
  for(index i = 0; i != 3; ++i) 
    for(index j = 0; j != 4; ++j)
      for(index k = 0; k != 2; ++k)
        A[i][j][k] = values++;

  // Verify values
  int verify = 0;
  for(index i = 0; i != 3; ++i) 
    for(index j = 0; j != 4; ++j)
      for(index k = 0; k != 2; ++k)
        assert(A[i][j][k] == verify++);

  return 0;
}