Data Structure and Algorithm

/*****************************************************************
 APPLICATION : Addition of Very Long Integers (using Linked List)
 CODED BY    : Ankit Pokhrel
 COMPILED ON : Borland C++ Ver 5.02
 DATE     : 2010 - July - 02
******************************************************************/

#include "iostream.h"
#include "conio.h"
#include "stdlib.h"

struct List //Structure to represent a node
{
 int data;
 struct List *next,*head,*Top;
};

typedef List node;
node *New;

void initialize(node **n) //Function to initialize a Node
{
 (*n)  = new node;
 (*n) -> next = NULL;
 (*n) -> head = NULL;
 (*n) -> Top == NULL;
}

void create(int Item) //Function to create a node
{
 New = new node;
 New -> next = NULL;
 New -> data = Item;
}

void push(node *n,int Item) //Function to add data to stack
{
 if(n -> Top == NULL) //if first item
  {
   n -> data = Item;
   n -> head = n;
   n -> Top = n;
   return;
  }

 create(Item);
 n -> Top -> next = New;
 n -> Top = New;
}

int pop(node *n) //Function to delete item from node
{
 if(n -> Top == NULL) //if no data
   return -999;

 node *poped,*temp = n -> head;
 if(n -> Top == n -> head)
  {
   poped = n -> head;
   n -> Top = NULL;
   n -> head = NULL;
   return poped -> data;
  }

 while(temp -> next != n -> Top) //traverse to second last node
  temp = temp -> next;

 poped = n -> Top;
 temp -> next = NULL;
 n -> Top = temp;
 return poped -> data;
}

void display(node *n,int carry) //Function to display the items of stack
{
 if(n -> Top == NULL) //if no Items
  {
   cout << "Stack is Empty.";
   return;
  }

 int rev[100],i = 0;
 node *temp = n -> head;
 rev[i++] = temp -> data; //save data to array
 while(temp -> next != NULL)
  {
   temp = temp -> next;
   rev[i++] = temp -> data;
  }

 if(carry)
  cout << carry;
 for(int j = i-1;j >= 0;j--) //Display data in reverse order
  cout << rev[j];
}

int main()
{
 node *opr1,*opr2,*result;
 //Initalize all nodes
 initialize(&opr1);
 initialize(&opr2);
 initialize(&result);

 char oprand1[100],oprand2[100],ch[2];
 //Scan Inputs
 cout << "Enter Number : ";
 cin >> oprand1;
 int i = 0,value,len1,len2,len;
 oprand1[i-1] = ' ';
 while(oprand1[i] != '\0')
  {
   ch[0] = oprand1[i];
   ch[1] = '\0';
   value = atoi(ch);
   push(opr1,value);
   i++;
  }

 len1 = i;

 cout << "Enter Number : ";
 cin >> oprand2;

 i = 0;
 oprand2[i-1] = ' ';
 while(oprand2[i] != '\0')
  {
   ch[0] = oprand2[i];
   ch[1] = '\0';
   value = atoi(ch);
   push(opr2,value);
   i++;
  }

 len2 = i;

 if(len1 > len2)
  len = len1;
 else
  len = len2;
 
 int value1,value2,value3,carry = 0;
 while(len > 0) //while data on largest Stack
  {
   value1 = pop(opr1); //pop data
   if(value1 == -999) //if no data
    value1 = 0; //set value1 to zero
   value2 = pop(opr2); //pop data
   if(value2 == -999) //if no data
     value2 = 0; //set value2 to zero

   value3 = value1 + value2 + carry; //Add all data
   carry = value3/10; //Find Carry
   if(carry)
    value3 -= 10 * carry; //Remove Carry part

   push(result,value3); //push result to different stack
   len--;
  }

 cout << "\nResult : ";
 display(result,carry); //Display result
 getch();
 return 0;
}