/* CS1711B - 1998/10/19
Modular arithmetic tables*/

#include <iostream.h>

void get_input(int& m);
/* the integer m is the modulus for use in the tables*/


//print header row function
void print_header(int modulus, char operation);

//print row function
void print_row(int row_count, int modulus, char operation);


int main()
{
  int modulus, row_count;
  char operation;



//input modulus

  get_input(modulus);

  cout << "\nThe modular arithmetic tables are\n";

// print + table
  //print header row for +
   operation = '+';
   print_header(modulus,operation);
  //initialize row count, print rows
   row_count = 0;
   while (row_count < modulus )
	{
	print_row(row_count, modulus, operation);
	row_count++;
	}
// print * table
  //print header row for *
   operation = '*';
   print_header(modulus,operation);
  //initialize row count, print rows
   row_count = 0;
   while (row_count < modulus )
	{
	print_row(row_count, modulus, operation);
	row_count++;
	}
  return 0;
}


// input function
void get_input(int& modulus)
  {
	int err_count = 0;
	cout << "\nEnter a positive integer > " << endl;
	cin >> modulus;

//trap for errors

	while ((modulus <= 0) && (err_count < 3))
	 { cout << "Input error - please enter  a POSITIVE integer >" << endl;
	   cin >> modulus;
	   err_count++;
	 }

	if (err_count >= 3)
	  cout << "Your table will contain errors!" << endl;

//	return modulus;  NOTE that we have deleted this!!!
  }



//print header row function
void print_header(int modulus, char operation)
  //print operator
  { cout << endl << endl << operation << "    ";
  //initialize column count, print column counts
	 for (int i = 0; i < modulus; i++)
		cout << i << "   ";
	 cout  << endl;
  }


//print row function
void print_row(int row_count, int modulus, char operation)
  //print row count
  //initialize column count, (print row + column)*modulus, increment col count
  {
   int col_count = 0;
   cout << row_count << "    ";
   while (col_count < modulus)
	{ if (operation =='+')
		cout << (row_count + col_count)%modulus << "   ";
	  else if (operation =='*')
		cout << (row_count * col_count)%modulus << "   ";
	  col_count++;
	}
	cout << endl;


  }