ernie.WPI.EDU> cat n_int.h

// file n_int.h, cs2223, D97/98
// class definition of an n-digit int implemented as a stack
// 01Mar98 NW First version

#ifndef N_INT_H
#define N_INT_H

/*** includes ***/
#include <fstream>
#include <iostream>
#include <memory>
#include <stack>
#include <vector>
#include <queue>

class n_int
	{
	private:
		stack <char> st; // the int
		void reverse(); // reverse the order in the stack
	public:
		void operator=(n_int); // overloaded replacement operator
		n_int operator+(n_int); // overloaded addition operator
		void get_file(char *name); // read a data file
		void put_file(char *name); // write a data file
		void print(int line_length); // print a number
	
	};
#endif // N_INT_H
// Copyright 1998 Norman Wittels

ernie.WPI.EDU> cat n_int.C

// file n_int.C, cs2223, D97/98
// code for n-digit integer class
// 01Mar98 NW First version

#include "n_int.h"

// private functions
void n_int::reverse() // reverse the order in the stack
	{
	queue <char> q; // temp holding place
	while (!st.empty()) // enqueue the stack
		{
		q.push(st.top());
		st.pop();
		}
	while(!st.empty()) st.pop(); // clear the stack
	while (!q.empty()) // dequeue into the stack
		{
		 st.push(q.front());
		 q.pop();
		}
	} // end reverse()

// public functions

void n_int::operator=(n_int other)
	{
	st = other.st; // copy the stack
	} // end operator=()

n_int n_int::operator+(n_int other) // overloaded addition operator
	{
	int sum, carry;
	n_int answer;
	stack <char> first, second; // temp stacks
	first = st;
	second = other.st;
	carry = 0;
	while (!first.empty() || !second.empty())
		{
		sum = 0;
		if (!first.empty())
			{
			sum += first.top();
			first.pop();
			}
		if (!second.empty())
			{
			sum += second.top();
			second.pop();
			}
		sum += carry;
		answer.st.push(sum%10);
		carry = sum/10;
		}
	if (carry != 0) answer.st.push(carry);
	answer.reverse(); // put answer in right order
	return answer;	
	} // end operator+();

void n_int::get_file(char *name) // read a data file
	{
	ifstream the_file;
	the_file.open(name); // open the file
	if (!the_file) // could not open the file
		{
		while(!st.empty()) st.pop(); // make sure the stack is empty
		return;
		}
	char temp;
	while (the_file >> temp) // read a digit
		{
		temp -= 48; // convert from char to a number
		if ((temp < 0) || (temp > 9)) temp = 0; // make sure it is a digit
		st.push(temp); // add to the stack
		}
	return;
	} // end get_file()

void n_int::put_file(char *name) // write a data file
	{
	ofstream the_file;
	the_file.open(name); // open the file
	if (!the_file) return; // could not open the file
	stack <char> temp_stack;
	temp_stack = st; // keep a copy because the later popping is destructive
	reverse(); // reverse the stack
	char temp;
	while (!st.empty()) // pop the whole stack
		{
		temp = st.top();
		st.pop();
		temp += 48; // convert from char to a number
		the_file << temp; // write to file
		}
	st = temp_stack; // restore the stack
	return;
	} // end put_file()

void n_int::print(int line_length) // write a data file
	{
	stack <char> temp_stack;
	temp_stack = st; // keep a copy because the later popping is destructive
	reverse(); // reverse the stack
	int temp;
	int count = 0;
	while (!st.empty()) // pop the whole stack
		{
		if (count >= line_length)
			{
			count = 0;
			cout << endl;
			}
		temp = st.top(); // get a digit
		st.pop();
		cout << temp; // print a digit
		count++;
		}
	st = temp_stack; // restore the stack
	return;
	} // end put_file()
// Copyright 1998 Norman Wittels

ernie.WPI.EDU> cat add_n.C

// file add_n.C, cs2223, D97/98 //
// program which performs n-digit addition //
// 08Mar98 NW, First version //

// includes //

#include <iostream>
#include "n_int.h"

int main ()
	{
	n_int n1, n2, n3; // the numbers
	
	n1.get_file("n1.dat");
	cout << "n1" << endl;
	n1.print(20);
	cout << endl << endl;
	n2.get_file("n2.dat");
	cout << "n2" << endl;
	n2.print(20);
	cout << endl << endl;
	n3 = n1 + n2;
	cout << "n3" << endl;
	n3.put_file("n3.dat");
	n3.print(20);
	cout << endl;
	
	return 0;
	} // end main()
// Copyright 1998 Norman Wittels

ernie.WPI.EDU> g++ *.C

ernie.WPI.EDU> a.out

n1
01234567890123456789
01234567890123456789
01234567890123456789
01234567890123456789
01234567890123456789
0

n2
96557316587678891032
16802647625346513035
46312346343636230300
58797455897951518186
87634684600635469846
84135894974981312198
4987603055789745

n3
96557316587678891032
16802647625346514270
03101358689315131535
15586468243630419421
44423696946314371081
40924907320660213433
0666504290357635

ernie.WPI.EDU>