STL General: How to declare and use two-dimensional arrays?
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Thread: STL General: How to declare and use two-dimensional arrays?

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    STL General: How to declare and use two-dimensional arrays ?

    Q: How can I define a dynamic two-dimensional array?

    A: The basic idea is to use a 'vector<vector<T> >'. Use containment to write a template class that offers the desired functionality. Following skeleton code shows how to implement and use such a class:

    Code:
    #include <vector>
    
    template <typename T>
    class dynamic_array
    {
    public:
      dynamic_array(){};
      dynamic_array(int rows, int cols)
      {
        for(int i=0; i<rows; ++i)
        {
          data_.push_back(std::vector<T>(cols));
        }
      }
      
      // other ctors ....
    
      inline std::vector<T> & operator[](int i) { return data_[i]; }
    
      inline const std::vector<T> & operator[] (int i) const { return data_[i]; }
    
      // other accessors, like at() ...
    
      void resize(int rows, int cols)
      {
        data_.resize(rows);
        for(int i = 0; i < rows; ++i)
          data_[i].resize(cols);
      }
    
      // other member functions, like reserve()....
    
    private:
      std::vector<std::vector<T> > data_;  
    };
    
    
    int main()
    {
      dynamic_array<int> a(3, 3);
      a[1][1] = 2;
      int x = a[1][1];
      return 0;
    }
    A different approach, not using the STL 'vector' class, is shown in the following FAQ...


    FAQ contributed by: [Gabriel Fleseriu] [Axter]


    Last edited by Andreas Masur; July 24th, 2005 at 12:55 PM.

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