Add Two Numbers Represented by Linked Lists in C++

This C++ program takes the values of two large numbers as input and displays the computed value node by node in the resultant linked list.

Here is the source code of the C++ program to display the addition of two large numbers using linked list. The C++ program is successfully compiled and run on DevCpp, a C++ compiler. The program output is also shown below.

```
/*
```

 * C++ Program to use Linked List and add two large Numbers

```
 */
```
```
#include<iostream>
```
```
#include<conio.h>
```
```
using namespace std;
```
```
int c = 0, c1 = 0;
```
```
struct node1
```
```
{
```
```
    node1 *link;
```
```
    int data1;
```

}*head = NULL, *m = NULL, *np1 = NULL, *ptr = NULL;

```
struct node
```
```
{
```
```
    node *next;
```
```
    int data;
```
```
}*start = NULL, *p = NULL, *np = NULL;
```
```
void store(int x)
```
```
{
```
```
    np1 = new node1;
```
```
    np1->data1 = x;
```
```
    np1->link = NULL;
```
```
    if (c == 0)
```
```
    {
```
```
        head = np1;
```
```
        m = head;
```
```
        m->link = NULL;
```
```
        c++;
```
```
    }
```
```
    else
```
```
    {
```
```
        m = head;    
```
```
        while (m->link != NULL)
```
```
        {
```
```
            m = m->link;
```
```
        }
```
```
        m->link = np1;
```
```
        np1->link = NULL;          
```
```
    }
```
```
}
```
```
void keep(int x)
```
```
{
```
```
    np = new node;
```
```
    np->data = x;
```
```
    np->next = NULL;
```
```
    if (c1 == 0)
```
```
    {
```
```
        start = np;
```
```
        p = start;
```
```
        p->next = NULL;
```
```
        c1++;
```
```
    }
```
```
    else
```
```
    {
```
```
        p = start;
```
```
        while (p->next != NULL)
```
```
        {
```
```
            p = p->next;
```
```
        }
```
```
        p->next = np;
```
```
        np->next = NULL;            
```
```
    }
```
```
}
```
```
void add()
```
```
{ 
```
```
    int i = 0;
```
```
    node1 *t = head;
```
```
    node *v = start;
```
```
    while (t != NULL)
```
```
    {
```
```
        if (v == NULL)
```
```
        {
```
```
            t->data1 = t->data1 + i;
```
```
            i = t->data1 / 10;
```
```
            t->data1 = t->data1 % 10;
```

            if (t->link == NULL && i == 1)

```
            {
```
```
                ptr = new node1;
```
```
                ptr->data1 = i;
```
```
                ptr->link = NULL;
```
```
                t->link = ptr;
```
```
                t = t->link;
```
```
            }
```
```
            t = t->link;
```
```
            continue;
```
```
        }   
```
```
        else
```
```
        {
```

            t->data1 = t->data1 + v->data + i;

```
            i = t->data1 / 10;
```
```
            t->data1 = t->data1 % 10;
```

            if (t->link == NULL && i == 1)

```
            {
```
```
                ptr = new node1;
```
```
                ptr->data1 = i;
```
```
                ptr->link = NULL;
```
```
                t->link = ptr;
```
```
                t = t->link;
```
```
            }
```
```
            t = t->link;
```
```
            v = v->next;
```
```
        }
```
```
    }           
```
```
}       
```
```
void traverse()
```
```
{
```
```
    node1 *q = head;
```
```
    int c = 0,i = 0;
```
```
    while (q != NULL)
```
```
    {
```
```
        q = q->link;
```
```
        c++;
```
```
    }
```
```
    q = head;
```
```
    while (i != c)
```
```
    {
```
```
        x[c - i - 1] = q->data1;
```
```
        i++;
```
```
        q = q->link;
```
```
    }
```

    cout<<"Result of addition for two numbers:";

```
    for (i = 0; i < c; i++)
```
```
    {
```
```
        cout<<x[i]<<"\t";
```
```
    }
```
```
}
```
```
void swap(int *a,int *b)
```
```
{
```
```
    int temp;
```
```
    temp = *a;
```
```
    *a = *b;
```
```
    *b = temp;
```
```
}
```
```
int main()
```
```
{
```
```
    int n, x, mod, mod1;
```

    cout<<"Enter the two numbers"<<endl;

```
    cin>>n;
```
```
    cin>>x;
```
```
    if (x > n)
```
```
    {
```
```
        swap(&x,&n);
```
```
    }
```
```
    while (n > 0)
```
```
    {
```
```
        mod = n % 10;
```
```
        n = n / 10;
```
```
        store(mod);
```
```
    }
```
```
    while (x > 0)
```
```
    {
```
```
        mod1 = x % 10;
```
```
        x = x / 10;
```
```
        keep(mod1);
```
```
    }
```
```
    add();
```
```
    traverse();
```
```
    getch();
```
```
}
```

 
Output
 
Enter the two numbers
564
1999
Result of addition for two numbers:2      5       6       3

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