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

[xsxixtxhx]

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 "'

Node' : no appropriate default constructor available

" 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;
}
//---------------------------------------------------------------------------

[Narue]

>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:

[xsxixtxhx]

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

Thanks

[Narue]

>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 );
}