multidimensional array using c++ vector Post: 302307677

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Top Forums Programming multidimensional array using c++ vector Post 302307677 by carl.alv on Thursday 16th of April 2009 04:27:30 AM

04-16-2009

Registered User

multidimensional array using c++ vector

Hi! I need to make dynamic multidimensional arrays using the vector class. I found in this page How to dynamically create a two dimensional array? - Microsoft: Visual C++ FAQ - Tek-Tips the way to do it in 2D, and now i'm trying to expand it to 3D but i don't understand how is the operator[] working, so i have problems. Here is my code:

Code:

#include <iostream>
#include <vector>
using namespace std;

template <typename T>
class Matrix {
protected:
  std::vector<std::vector<T> > m_data;
public:
  Matrix() {}
  Matrix(int rows, int cols) : m_data(rows, std::vector<T>(cols)) {}
  ~Matrix() {}

  inline void get_size(int& rows, int& cols) {
    rows = m_data.size();
    cols = m_data[0].size(); }
  //operators
  inline std::vector<T> & operator[](int i) { return m_data[i]; }
  inline const std::vector<T> & operator[] (int i) const { return m_data[i]; }
};

template <typename T>
class MatrixTD {
protected:
  Matrix<std::vector<T> > m_data; 
  
public:
  MatrixTD() {}
  MatrixTD(int rows, int cols, int lays) : m_data(rows, cols) {
    for(int i = 0; i < rows; ++i)
      for(int j = 0; j < cols; ++j)
	m_data[i][j].resize(lays); }
  MatrixTD(int rows, int cols, int lays, T val) : m_data(rows, cols) {
    for(int i = 0; i < rows; ++i){
      for(int j = 0; j < cols; ++j){
	m_data[i][j].resize(lays);
	for(int k = 0; k < lays; ++k)
	  m_data[i][j][k] = val;
      }
    } }
  ~MatrixTD() {}
  
  inline void get_size(int& rows, int& cols, int& lays) {
    m_data.get_size(rows, cols);
    lays = m_data[0][0].size(); }
  //operators
  inline std::vector<T> & operator[](int i) { return m_data[i]; }
  inline const std::vector<T> & operator[] (int i) const { return m_data[i]; }
};

int main(){
  int size = 5;
  int s1, s2, s3;
  MatrixTD<int> m3Dd(size, size, size, 0);
  m3Dd.get_size(s1, s2, s3);
  for(int i = 0; i < s1; ++i){
    for(int j = 0; j < s2; ++j){
      for(int k = 0; k < s3; ++k){
	cout<<m3Dd[i][j][k]<<" ";
      }
      cout<<endl;
    }
    cout<<endl;
  }

  return 0;
}

And the compiler tels me:

vector3D.cpp: In member function �std::vector<T, std::allocator<_CharT> >& MatrixTD<T>::operator[](int) [with T = int]':
vector3D.cpp:113: instantiated from here
vector3D.cpp:47: error: invalid initialization of reference of type �std::vector<int, std::allocator<int> >&' from expression of type �std::vector<std::vector<int, std::allocator<int> >, std::allocator<std::vector<int, std::allocator<int> > > >'

Note: I can access the data if I make m_data public and I use m_data[][][], but the operator[] doues not work in the 3D case.

Thank you in advance for any help!

Last edited by Yogesh Sawant; 04-17-2009 at 06:02 AM.. Reason: removed smilies in text

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