Revise the code below to overload the stream extraction operator
(i.e., >>) and the stream insertion operator (i.e., <<).
In the case of the stream extraction operator, output should be to the
screen and to a file.

#include <iostream>
#include <iomanip>

using namespace std;

int ReadSquareSize();
void OddMagicSquare(int** matrix, int n);
void DoublyEvenMagicSquare(int** matrix, int n);
void SinglyEvenMagicSquare(int** matrix, int n);
void MagicSquare(int** matrix, int n);
int** CreateMatrix(int n);
void FreeMatrix(int** matrix, int n);

int main(int argc, char* argv[])
{
  int i,n;
  n = ReadSquareSize();

  int** matrix = CreateMatrix(n);

  MagicSquare(matrix, n);  

  // print the square
  for(int i=0; i<n ;i++)
  {
      for(int j=0; j<n ; j++)
      {
      cout<<setiosflags(ios::left) << setw (5) << matrix[i][j];        
      }
      cout<<endl;
  }
  
  FreeMatrix(matrix,n);
    
  return 0;
}


int ReadSquareSize()
{
    int x; 
    cout<<"Enter a positive integer square size of 3 or more: ";
    while(1)
    {
        cin>>x;
        if(x>=3)
        {
            return x;
        }
        else 
        {
            cout<<"Enter a positive integer square size of 3 or more: ";
        }
    }
    cout<<endl;
}

void MagicSquare(int** matrix,int n)
{
  if (n%2==1)        //n is Odd
    OddMagicSquare(matrix, n);
  else          //n is even
    if (n%4==0)    //doubly even order
      DoublyEvenMagicSquare(matrix, n);
    else      //singly even order
      SinglyEvenMagicSquare(matrix, n);
}

void OddMagicSquare(int** matrix, int n)
{
  int nsqr = n * n;
  int i=0, j=n/2;     // start position

  for (int k=1; k<=nsqr; ++k) 
  {
    matrix[i][j] = k;

    i--;
    j++;

    if (k%n == 0) 
    { 
      i += 2; 
      --j; 
    }
    else 
    {
      if (j==n) 
        j -= n;
      else if (i<0) 
        i += n;
    }
  }
}

void DoublyEvenMagicSquare(int** matrix, int n)
{
  int i, j;

  int** I = CreateMatrix(n);
  int** J = CreateMatrix(n);


  //prepare I, J
  int index=1;
  for (i=0; i<n; i++)
    for (j=0; j<n; j++)
    {
      I[i][j]=((i+1)%4)/2;
      J[j][i]=((i+1)%4)/2;
      matrix[i][j]=index;
      index++;
    }

  for (i=0; i<n; i++)
    for (j=0; j<n; j++)
    {
      if (I[i][j]==J[i][j])
        matrix[i][j]=n*n+1-matrix[i][j];
    }

  FreeMatrix(I,n);
  FreeMatrix(J,n);
    
}

void SinglyEvenMagicSquare(int** matrix, int n)
{
  int i, j, k, index=0;

  int p=n/2;

  int** M = CreateMatrix(p);
  
  MagicSquare(M, p);
  
  for (i=0; i<p; i++)
    for (j=0; j<p; j++)
    {
      matrix[i][j]=M[i][j];
      matrix[i+p][j]=M[i][j]+3*p*p;
      matrix[i][j+p]=M[i][j]+2*p*p;
      matrix[i+p][j+p]=M[i][j]+p*p;
    }

  if (n==2)
    return;  

  int* I = new int[p];
  int* J = new int[n];

  for (i=0; i<p; i++)
    I[i]=i+1;

  k=(n-2)/4;
  
  for (i=1; i<=k; i++)
    J[index++] = i;

  for (i=n-k+2; i<=n; i++)
    J[index++] = i;

  int temp;
  for (i=1; i<=p; i++)
    for (j=1; j<=index; j++)
    {
      temp=matrix[i-1][J[j-1]-1];
      matrix[i-1][J[j-1]-1]=matrix[i+p-1][J[j-1]-1];
      matrix[i+p-1][J[j-1]-1]=temp;
    }

  //j=1, i
  //i=k+1, k+1+p
  i=k; 
  j=0;
  temp=matrix[i][j]; matrix[i][j]=matrix[i+p][j]; matrix[i+p][j]=temp;

  j=i;
  temp=matrix[i+p][j]; matrix[i+p][j]=matrix[i][j]; matrix[i][j]=temp;

  FreeMatrix(M,p);
  delete[] I;
  delete[] J;
  
}


int** CreateMatrix(int n)
{
  int i;
  int** matrix = new int* [n];
  for(i=0;i<n;i++)
  {
        matrix[i] = new int[n];
  }
  return matrix;
}


void FreeMatrix(int** matrix, int n)
{
  for(int i=0; i<n ;i++)
  {
      delete[] matrix[i];
  }
  free(matrix);
}

---

Request for Question Clarification by studboy-ga on 31 Jul 2004 09:22 PDT

Hi forsight-ga

You mean overloading it to output to both file and stream?
(What's the file name?)
Or overloading it for in/outputing something else?

Also currently it does not compile due to an implicit
declaation of free--what's your compiler?

Thanks!

---

Clarification of Question by forsight-ga on 01 Aug 2004 00:16 PDT

I an such a newbie at this it's not funny but, I am using MS Visual
Studio .Net 2003. I haven't done any upgrades, so whatever compiler
comes out of the box is the compiler I am using.

Yes, I am asking to output to file and stream.  File Magic Square
under root directory C:\

Here is a simple solutions.  

Move the printing logic to a separate function say print.
void print(ostream& opStream)
{ 
 // print the square
  for(int i=0; i<n ;i++)
  {
      for(int j=0; j<n ; j++)
      {
      opStream<<setiosflags(ios::left) << setw (5) << matrix[i][j];        
      }
      opStream<<endl;
  }
}

then from your main method call print twice, one to log data to
console and one to log data to file.

// This will print data to console
print(cout);

ofstream outFile("c:/File Magic Square");
print(outFile);

you would need to pass n and the matrix as argument to the print method.