Pointer-to-pointer dynamic two-dimensional array

Question

First timer on this website, so here goes..

I\'m a newbie to C++ and I\'m currently working through the book \"Data structures using C++ 2nd ed, of D.S. Malik\".

Answer 1

This code works well with very few requirements on external libraries and shows a basic use of int **array.

This answer shows that each array is dynamically sized, as well as how to assign a dynamically sized leaf array into the dynamically sized branch array.

This program takes arguments from STDIN in the following format:

2 2   
3 1 5 4
5 1 2 8 9 3
0 1
1 3

Code for program below...

#include 

int main()
{
    int **array_of_arrays;

    int num_arrays, num_queries;
    num_arrays = num_queries = 0;
    std::cin >> num_arrays >> num_queries;
    //std::cout << num_arrays << " " << num_queries;

    //Process the Arrays
    array_of_arrays = new int*[num_arrays];
    int size_current_array = 0;

    for (int i = 0; i < num_arrays; i++)
    {
        std::cin >> size_current_array;
        int *tmp_array = new int[size_current_array];
        for (int j = 0; j < size_current_array; j++)
        {
            int tmp = 0;
            std::cin >> tmp;
            tmp_array[j] = tmp;
        }
        array_of_arrays[i] = tmp_array;
    }


    //Process the Queries
    int x, y;
    x = y = 0;
    for (int q = 0; q < num_queries; q++)
    {
        std::cin >> x >> y;
        //std::cout << "Current x & y: " << x << ", " << y << "\n";
        std::cout << array_of_arrays[x][y] << "\n";
    }

    return 0;
}

It's a very simple implementation of int main and relies solely on std::cin and std::cout. Barebones, but good enough to show how to work with simple multidimensional arrays.