Re: [Dev-C++] linked lists

[Jason H. <jas...@bt...>]

Also in the  Create() function you create a node and put it the list pointer
you create, then you overwrite that pointer with NULL, which is a memory
leak as you don't deallocate the node you created. Also the function doesn't
return anything.

Jason.

----- Original Message -----
From: "Williams, Timothy W." <TIM...@sa...>
To: "'chromatonus 712'" <chr...@ho...>;
<dev...@li...>
Sent: Friday, November 09, 2001 11:07 PM
Subject: RE: [Dev-C++] linked lists


> In your main(), when you declare your first pointer to a node you need to
> set that equal to NULL or 0.  The problem you were having is when you add
> you were taking whatever address that was in list and just plunking it
right
> in ->next which isn't so bad if it's a good address but the way it was
> written, when you were displaying it, it looped fine, but never got to
NULL
> and instead just trotted off into memory.
> node *list = NULL;
> instead of...
> node *list;
>
> --tim
>
> > -----Original Message-----
> > From: chromatonus 712 [mailto:chr...@ho...]
> > Sent: Friday, November 09, 2001 5:44 PM
> > To: dev...@li...
> > Subject: [Dev-C++] linked lists
> >
> >
> > hi, if you'd like to help, this is a menu of functions doing
> > operations on a
> > linked list, and i have a runtime error after i performed
> > add_front() and
> > displayed the list. The correct list was displayed but the
> > error message
> > came right after. Can you please find out what's wrong? Thank you!
> >
> > and, is there an equivalent expression for the Borland
> > gotoxy() in Dev?
> > thanks
> >
> > #include <iostream.h>
> > #include <conio.h>
> > #include <stdlib.h>
> > #include <math.h>
> >
> >
> > struct node
> > {
> >    int data;
> >    node *next;
> > };
> >
> >
> > //PROTOTYPES
> >
> > int menu();
> > node create();
> > node add_front(node *&list, int info);
> > //node add_back(node *&list);
> > node delete_from(node *&list);
> > void display(node *list);
> > void exit();
> >
> >
> > int menu()
> > {
> >    int choice;
> >
> >    cout<< "LINKED LIST EDITOR MENU OPTIONS" << "\n";
> >
> >    cout<< "1.  Create List" << "\n";
> >    cout<< "2.  Add to Front of List" << "\n";
> >    cout<< "3.  Add to Back of List" << "\n";
> >    cout<< "4.  Display List" << "\n";
> >    cout<< "5.  Delete from List" << "\n";
> >    cout<< "10. Exit" << "\n" << "\n";
> >    cout<< "choice? ";
> >    cin>> choice;
> >    return(choice);
> > }
> >
> > int main()
> > {
> >    node *list;
> >    int choice, info;
> >    choice = menu();
> >    while( choice != 10 )
> >    {
> >       switch( choice )
> >       {
> >          case 1:  create();
> >                   break;
> >          case 2:
> >
> >                   cout<< "input?  ";
> >                   cin>> info;
> >                   add_front(list, info);
> >                   cout<< "choice? ";
> >                   cin>> choice;
> >                   break;
> >
> >          //case 3:  add_back(list);
> >          //         break;
> >          case 4:  display(list);
> >                   cout<< "choice? ";
> >                   cin>> choice;
> >                   break;
> >          case 5:  delete_from(list);
> >                   cout<< "choice? ";
> >                   cin>> choice;
> >                   break;
> >          case 10: exit();
> >                   break;
> >          choice = menu();
> >       }
> >    }
> >
> > }
> >
> >
> > node create()
> > {
> >    node *list = new node;
> >    list = NULL;
> > }
> >
> > node add_front(node *&list, int info)
> > {
> >
> >    node *head = new node;
> >    head -> data = info;
> >    head -> next = list;
> >    list = head;
> >
> >
> > }
> >
> > //node add_back(node *&list)
> > //{
> > //   int info;
> > //   cout<< "input? ";
> > //   cin>> info;
> > //   if (list == NULL)
> > //   {
> > //      node *tail = new node;
> > //      tail -> next = NULL;
> > //      list -> next = tail;
> > //   }
> > //   else
> > //   {
> > //      node *tail = new node;
> > //      tail -> next = NULL;
> > //      tail -> next = tail;
> > //   }
> > //}
> >
> > node delete_from(node *&list)
> > {
> >    int info;
> >    node *hold, *jump;
> >    cout<< "number to delete? ";
> >    cin>> info;
> >    hold = list;
> >    jump = hold -> next;
> >    while(hold != NULL)
> >    {
> >       if(hold -> data == info)
> >       {
> >          hold = jump;
> >          list -> next = jump;
> >          jump = hold -> next;
> >       }
> >       else
> >       {
> >          hold = jump;
> >          jump = hold -> next;
> >       }
> >    }
> > }
> >
> > void display(node *list)
> > {
> >    while(list != NULL)
> >    {
> >       cout<< list -> data << "   ";
> >       list = list -> next;
> >    }
> >    system("PAUSE");
> > }
> >
> > void exit()
> > {
> >    system("PAUSE");
> > }
> >
> >
> > _________________________________________________________________
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>
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