//
// demonstrates two dimensional row-dominate arrays
// internal representation is a continguous block of memory with ascending 
// addresses corresponding to ascending columns
//
// for example
//
// the 2d array :
// 0,0  0,1  0,2
// 1,0  1,1  1,2
// 2,0  2,1  2,2
//
// can be represented in memory using a 1d array as :
// 0,0  0,1  0,2  1,0  1,1  1,2  2,0  2,1  2,2
//
// calculating the index into the 1d array is done by computing a row,column index relative to zero
// and then multiplying the row index by the length of a row (also the number of columns) and adding 
// the column index
//
// Written by Maxwell Sayles, 2001, for CPSC331, University of Calgary
//

#include <iostream>
#include <iomanip>
using namespace std;

//
// 2d array class
//
class Array2d
{
public:
	Array2d (int rowLowIndex, int rowHighIndex, int columnLowIndex, int columnHighIndex);
	~Array2d();
	
	int getItem (int row, int column);
	void setItem (int row, int column, int value);
	
	int getRowLowIndex()		{ return this->rowLowIndex; }
	int getRowHighIndex()		{ return this->rowHighIndex; }
	int getColumnLowIndex()		{ return this->columnLowIndex; }
	int getColumnHighIndex()	{ return this->columnHighIndex; }

	// returns the number of rows
	int getRowCount()			{ return this->rowHighIndex - this->rowLowIndex + 1; }	
	// returns the number of columns
	int getColumnCount()		{ return this->columnHighIndex - this->columnLowIndex + 1; }
	
	int getArea()				{ return this->getRowCount() * this->getColumnCount(); }
	
private:
	int rowLowIndex;
	int rowHighIndex;
	int columnLowIndex;
	int columnHighIndex;

	int* data;
};


//
// construct an array with the specified row,column bounds
// bounds are inclusive
//
Array2d::Array2d (int rowLowIndex, int rowHighIndex, int columnLowIndex, int columnHighIndex)
{
	this->rowLowIndex		= rowLowIndex;
	this->rowHighIndex		= rowHighIndex;
	this->columnLowIndex	= columnLowIndex;
	this->columnHighIndex	= columnHighIndex;
	
	this->data = new int [this->getArea()];
}

//
// destruct the array
// delete the data member
Array2d::~Array2d()
{
	delete[] this->data;
}


//
// return the item at the specified row,column
//
int Array2d::getItem (int row, int column)
{
	int baseRow		= row - this->rowLowIndex;
	int baseColumn	= column - this->columnLowIndex;
	int index		= baseRow*this->getColumnCount() + baseColumn;

	return this->data[index];
}


//
// set the item at the specified row,column
//
void Array2d::setItem (int row, int column, int value)
{
	int baseRow		= row - this->rowLowIndex;
	int baseColumn	= column - this->columnLowIndex;
	int index		= baseRow*this->getColumnCount() + baseColumn;
	
	this->data[index] = value;
}


//
// program entry
//
int main()
{
	int row = 0;
	int column = 0;

	// get bounds of table from user input
	int rowLowIndex = 0;
	int rowHighIndex = 0;
	int columnLowIndex = 0;
	int columnHighIndex = 0;
	
	cout << "Enter the row low index (e.g. 16): ";
	cin >> rowLowIndex;
	cout << "Enter the row high index (e.g. 32): ";
	cin >> rowHighIndex;
	cout << "Enter the column low index (e.g. 24): ";
	cin >> columnLowIndex;
	cout << "Enter the column high index (e.g. 36): ";
	cin >> columnHighIndex;

	cout << endl << endl;


	// create 2d array
	Array2d table (rowLowIndex, rowHighIndex, columnLowIndex, columnHighIndex);
	
	// build multiplication table
	for (row = table.getRowLowIndex();  row <= table.getRowHighIndex();  row ++)
	{
		for (column = table.getColumnLowIndex();  column <= table.getColumnHighIndex();  column ++)
		{
			table.setItem (row, column, row*column);
		}
	}
	
	// print rows across the top
	cout << " x  ";
	for (column = table.getColumnLowIndex();  column <= table.getColumnHighIndex();  column ++)
	{
		cout << setw(4) << column << ' ';
	}
	cout << endl << endl;
	
	for (row = table.getRowLowIndex();  row <= table.getRowHighIndex();  row ++)
	{
		cout << setw(2) << row << "  ";
		for (column = table.getColumnLowIndex();  column <= table.getColumnHighIndex();  column ++)
		{
			int value = table.getItem (row, column);
			cout << setw(4) << value << ' ';
		}
		cout << endl;
	}
	
	cout << endl << endl;	
	
	return 0;
}