Using a class to add/delete/show numbers in a Link List
 

I have this program that is supposed to take in numbers from the Main cpp file and add them to the link list. Eventually i have to sort them then display them on the screen. For right now i am just trying to insert them to the link list but i keep getting a complie error. I am trying to compile this program and i get the following error "'[HTML]Node' : no appropriate default constructor available[/HTML]" Any suggestions ?

I have attached a link to the files in case it is easier for you to view it that way
Project 3

Thanks

Here is my .h file which creates the file currently i am trying to get the Insert Fuction to work so i have the other set as commetns

 //---------------------------------------------------------------------------

#ifndef RcrLnkListH

#define RcrLnkListH

//---------------------------------------------------------------------------

typedef int Item;



class List

{

public:

   List();// head(0) { }; 

   ~List();



   bool IsEmpty();



  void Show();

   bool Insert( Item item ); 

      //{ return Insert( head, item ); }

   //bool Delete( Item item );  

      //{ return Delete( head, item ); }*/



private:

   struct Node

   {

      Item item;

      Node *next;



      Node( Item itm, Node * nxt ) 

                  : item(itm), next(nxt) { }

   };



   Node * head;



   void Show( Node * node );

   bool Insert( Node * &node, Item item );

   /*bool Delete( Node * & node, Item item );*/

};

//---------------------------------------------------------------------------

#endif

 

Here is my implemtation file which define the functions in the class:

#include <iostream>

#include <iomanip>

#include <cstdlib>

#pragma hdrstop

#include "RcrLnkListH.h"

using namespace std;





List:: List(): head(0) { }; 





   

List:: ~List()

{

}





bool List:: IsEmpty()

{

        return head ==0;

}

   



void List:: Show()

{

void Show( Node * node );



}





void List::Show(Node *node)

{

if (node != NULL)

                cout<<node->item;

                Show(node->next);



}



bool List:: Insert( Item item ) 

      { 

                

                bool Insert( Node * &node, Item item );

                return Insert( head, item ); }



          

bool List:: Insert( Node * &node, Item item ) 

{

        if ((node == NULL) || (item < node->item))

        {

                

                Node *newPtr = new Node ;

                if (newPtr == NULL)

                {}

                else

                {

                        newPtr->item = item;

                        newPtr->next = node;

                        node = newPtr;

                }

        }

        else Insert(node->next, item);

return Insert( head, item );

}

   

/*bool Delete(Node * & node, Item item)  

      { return Delete( head, item ); }*/

Finally here is my Main CPP file

//---------------------------------------------------------------------------

#include <iostream>

#pragma hdrstop

#include "RcrLnkListH.h"

using namespace std;

//---------------------------------------------------------------------------



int main(int argc, char* argv[])

{

   List list;



   if (list.IsEmpty == 0)

   {

           cout<<"not";

   }

   else 

           cout<<"is empty";

   list.Show();



   list.Insert(3);

   //list.Insert(1);

   //list.Insert(2);

   //list.Insert(5);

  // list.Insert(4);



   list.Show();



  // list.Delete(3);   list.Show();

  // list.Delete(1);   list.Show();

  // list.Delete(5);   list.Show();*/



   cin.get();

   return 0;

}

//---------------------------------------------------------------------------

Re: Using a class to add/delete/show numbers in a Link List
 

>Node *newPtr = new Node ;
You're trying to use a constructor with no arguments, yet your Node is declared as:

struct Node

{

   Item item;

   Node *next;



   Node( Item itm, Node * nxt ) 

        : item(itm), next(nxt) { }

};

Notice how the only constructor declared takes two arguments. If you declare any constructors then the default constructor is not created automagically for you.

>Any suggestions ?
Be prepared for a good time trying to get this program to work. :mrgreen:

Re: Using a class to add/delete/show numbers in a Link List
 

does anyone have any hits on how i can redo the implemenation of Insert to get this to work ?

Thanks

Re: Using a class to add/delete/show numbers in a Link List
 

>does anyone have any hits on how i can redo the implemenation of Insert to get this to work ?
Don't use recursion. Not only does it complicate a simple algorithm, it's potentially dangerous for long lists. I generally prefer to avoid recursion for linear data structures. If you can't efficiently divide the structure in half then that's an indication that recursion may not be the best solution.

#include <cstdlib>

#include <iostream>



using namespace std;



struct node {

  int data;

  node *next;



  node ( int init, node *link )

    : data ( init ), next ( link )

  {}

};



node *insert ( node *list, int data )

{

  if ( list == 0 ) {                // Empty list

    list = new node ( data, 0 );

  } else if ( data < list->data ) { // New head

    list = new node ( data, list );

  } else {                          // Everywhere else

    node *it = list;



    while ( it->next != 0 && data > it->next->data )

      it = it->next;



    it->next = new node ( data, it->next );

  }



  return list;

}



void print ( node *list )

{

  while ( list != 0 ) {

    cout<< list->data <<' ';

    list = list->next;

  }



  cout<<endl;

}



int main()

{

  node *list = 0;



  for ( int i = 0; i < 10; i++ )

    list = insert ( list, rand() % 100 );



  print ( list );

}