C++ Help on Linked List

[Joshua_143]

So i wrote a program which take 2 linked lists and merges them but for some reason it does not work!!!!
it gets complied 0 ERRORS 0 WARNINGS
but for some reason (logical i think) it does not merge properly

#include <iostream>
#include <iomanip>
#include <conio.h>

using namespace std;

class llist
{
  struct node
   {
     int data;
     node *link;

   }*start1,*start2,*start3;
public:
  llist(){start1 = start2 = start3 = NULL ;}
  void create();
  void display();
  void display_second();
  void mergef();
  ~llist();
};

void llist :: create()
 {

   int n,i,m;
   cout << "How many nodes you want to create?" << endl;
   cin >> n;
   cout<<endl;
   node *first,*last,*temp;
   first = new node;
   cout<<"Enter the data part of node 1"<<endl;
   cin>>first->data;
   first->link = NULL;
   temp = first;

for (i = 1;i<n;i++){
  last = new node;
  cout << "Enter the data part of node "<<i+1<<endl;
  cin >> last ->data;
  last ->link = NULL;
  temp -> link = last;
  temp = last;
        }
start1 = first;

cout<<"-----------------------------------------------------------"<<endl;

     cout<<endl<<"How many nodes do you want to create in linked list 2?"<<endl;
     cin >> m;
     cout<<endl;
     node *one ,*sec,*t;
     one = new node;
     cout<<"Enter the data part of the 1 node"<<endl;
     cin>>one ->data;
     one -> link = NULL;
     t = one;

    for(i = 1; i < m ;i++)
       {
      sec = new node;
      cout << "Enter the data part of the "<<i+1<<" node"<<endl;
      cin >> sec -> data;
      sec -> link = NULL;
      t -> link = sec;
      t = sec;
       }
   start2 = one;
 }

void llist :: mergef()
 {
   node *p ,*temp1,*temp2,*last;

   p = new node;
   p->link = NULL;

  for (temp1 = start1,temp2 = start2;(temp1 != NULL) && (temp2 != NULL) ;)
    {
      if ((temp1->data) < (temp2->data))
      {
        p -> data = temp1 ->data;
        temp1 = temp1 -> link;
      }
        else
          {
        p -> data = temp2->data;
        temp2 = temp2->link;
          }
      if(start3 == NULL)
          start3 = p;
          else
             last->link = p;

      last = p;
    }

   for(;temp1!=NULL;temp1 = temp1->link)
    {
        p = new node;
        p -> data = temp1->data;
        p -> link = NULL;
        last ->link = p;
        last = p;
    }

   for(;temp2!=NULL;temp2 = temp2->link)
    {
        p = new node;
        p->data = temp2->data;
        p->link = NULL;
        last->link = p;
        last = p;

    }
 }

   void llist :: display_second()
    {
  cout<<"The Merged LinkList is as follows"<<endl;
    node *p = start3;
    while (p!=NULL)
    {
        cout << p->data<<"->";
        p = p->link;
    }
    cout<<"END"<<endl<<endl;
   }


 void llist :: display()
  {

      cout<<endl<< "The first Linked List is as follows"<<endl;
      node *p  = start1;
      node *p2 = start2;
      while(p!=NULL)
      {
          cout << p->data<<"->";
          p = p->link;
      }
      cout<<"END"<<endl<<endl;

      cout<<"The second Linked List is as follows"<<endl;

     while(p2!= NULL)
     {
         cout<<p2->data<<"->";
         p2 = p2->link;
     }
     cout<<"END"<<endl;
  }


  llist :: ~llist()
  {
      node *p = start1;

      while(start1!=NULL)
      {
          p = start1->link;
          delete start1;
          start1 = p;

      }
  }

  int main()
  {
      llist l;
      int ch;
      //system("cls");
      do{
            cout<<endl<<"1)Create and display the two linked lists"<<endl<<"2)Merge the 2 linked list"<<endl;
            cout<<"3)Exit"<<endl;
            cin>>ch;

            switch(ch)
            {
            case 1:
                l.create();
                l.display();
                break;
            case 2:
                l.mergef();
                l.display_second();
                break;
            case 3:
                break;
            default:
                cout<<"Wrong Option"<<endl;

            }

      }while(ch!=3);

    return 1;
  }

 

[ex_bubblehead]

This looks suspiciously like a homework assignment:

http://www.tomshardware.com/forum/244553-49-read-programming-assignment-help

We will help guide you but we won't do all the work for you.

 

[rgd1101]

Use debug, compile only test for syntax error, not logic error

 

[Joshua_143]

can you at least compile the code on your system and see if it works

 

[rgd1101]

can you at least compile the code on your system and see if it works

It your homework. And you said it compiled. Run it in debug.

 

[ex_bubblehead]

can you at least compile the code on your system and see if it works

And what have you done to troubleshoot this code?

What is the input?
What is the expected output?

Have you single stepped the code, recording the intermediate values at every step and comparing to expected values?

As already stated, this is your homework and we're not going to do your work for you.