//	Ex642.cc

//	Sec. 6.4 of lecture
//	Dynamic arrays 2D

#include <iostream.h>

main()
{
  int     n,m,i,j;
  double  *a, **b;
  
  cout << "  Eingabe Zeilen  n : ";  cin >> n;
  cout << "  Eingabe Spalten m : ";  cin >> m;

//--------------------------------------------------------------------
//			Version a  
  a = new double[n*m];			//	Allocate array

// 		initialize a
  for (i = 0; i < n; i++ )
   {
     for (j = 0; j < m; j++)
      {
        a[i*m+j] = (i+1)*(j+1);
      }
   } 
   
//		output a;
  cout << endl << "  Matrix A " << endl;
  for (i = 0; i < n; i++ )
   {
     for (j = 0; j < m; j++)
      {
        cout <<  "  " << a[i*m+j];
      }
     cout << endl;
   } 
  cout << endl;
  
  delete [] a;				//	Deallocate array

//--------------------------------------------------------------------
//			Version b  (even more dynamic)
//					Pointers at pointers

  b = new (double* [n]);		//	Allocate row pointers
  for (i = 0; i < n; i++)
   {
     b[i] = new double[m];		//	Allocate rows
   }
//		There is no guarantee that the rows are stored
//		linearly in memory

 // 		initialize b
  for (i = 0; i < n; i++ )
   {
     for (j = 0; j < m; j++)
      {
        b[i][j] = (i+1)*(j+1);
      }
   } 
  
//		output b;
  cout << endl << "  Matrix B " << endl;
  for (i = 0; i < n; i++ )
   {
     for (j = 0; j < m; j++)
      {
        cout <<  "  " << b[i][j];
      }
     cout << endl;
   } 
  cout << endl;
  
  for (i = n-1; i >= 0; i--)
   {
     delete [] b[i];			//	Deallocate rows
   }
  delete [] b;				//	Deallocate row pointers

}