Create a two-dimensional array at runtime

Get two integers from the user, then create a two-dimensional array where the two dimensions have the sizes given by those numbers, and which can be accessed in the most natural way possible. Write some element of that array, and then oputput that element. Finally destroy the array if not done by the language itself.

C++

With language built-in facilities:

#include <iostream>
#include <istream>
#include <ostream>

int main()
{
  // read values
  int dim1, dim2;
  std::cin >> dim1 >> dim2;

  // create array
  double* array_data = new double[dim1*dim2];
  double** array = new double*[dim1];
  for (int i = 0; i < dim1; ++i)
    array[i] = array_data + dim2*i;

  // write element
  array[0][0] = 3.5;

  // output element
  std::cout << array[0][0] << std::endl;

  // get rid of array
  delete[] array;
  delete[] array_data;
}

Using std::vector from the standard library:

#include <iostream>
#include <istream>
#include <ostream>
#include <vector>

int main()
{
  // read values
  int dim1, dim2;
  std::cin >> dim1 >> dim2;

  // create array
  std::vector<std::vector<double> > array(dim1, std::vector<double>(dim2));

  // write element
  array[0][0] = 3.5;

  // output element
  std::cout << array[0][0] << std::endl;

  // the array is automatically freed at the end of main()
}