Please Help! Linked List with Classes Problem

l3rian

I would really appreciate some help with this small problem, that I have encountered.

I am trying to declare a linked list with a class of members in it. This is my problem:

I have to initalise the membership class in the linked list, therefore the linked list must come after the class. But I need to declare the linkedlist in the public function prototype of new_membership in the class.

Anyone see a way in which I can have my linked list with the membership class in it? Please help if you can

Here is the start of the program:

#include <stdio.h>
#include <iostream.h>
#include <stdlib.h>
#include <string.h>
#include <iomanip.h>


class membership
{
public:
membership();
~membership();

void new_membership(LISTNODEPTR *);
void display();

private:
int account_number;
char first_name[20];
};

struct listnode
{
membership member;
struct listnode *nextptr;
};
typedef struct listnode LISTNODE;
typedef LISTNODE *LISTNODEPTR;


int main()
{
int i,j,chc;
LISTNODEPTR member_list = NULL;
do
{
chc = menu();

switch (chc)
{
case 1:
void new_membership(&member_list);
break;
.
.
.


Am I going about this the wrong way, If you can help me at all, I would really apreciate it

Brian

Typedef

Behold the shoe.... ah yes... the shoe...

http://www.boards.ie/vbulletin/showthread.php?s=&threadid=67660

"
I'm not an addict... I'm not... I'm not...
Can I get some more coffee?
"

l3rian

Thanks for your help typedef

I couldnt find what I was looking for in that link, but I have abandoned the idea of a linked list containing a class. It doesnt seem possible because one must requires the other to be defined first. So, instead I have initalised an array of classes, not as memory effectant, but simpler to do

Gavin

yeah, don't like using structs meself.
would stick it into a class,

and when you are creating a class A that references B, & B references A you have to forward declare the class.

have a look around on the internet for more details.

basicly before you declare your class, you do

class LinkedList ;

class membership
{

} ;

Gav

Mr.StRiPe

This should do it. Only one extra line (in red) enjoy!


#include <stdio.h>
#include <iostream.h>
#include <stdlib.h>
#include <string.h>
#include <iomanip.h>


class membership
{

struct LISTNODEPTR;

public:
membership()
~membership()

void new_membership(LISTNODEPTR *);
void display();

private:
int account_number;
char first_name[20];


};

struct listnode
{
membership member;
struct listnode *nextptr;
};


typedef struct listnode LISTNODE;
typedef LISTNODE *LISTNODEPTR;


void main()
{
int i,j,chc;

LISTNODEPTR member_list = NULL;

while(true)
{
chc = menu();

switch (chc)
{
case 1:
void new_membership(&member_list); break;

}
}

}

Mr.StRiPe

This should do it. Only one extra line (in red) enjoy!


#include <stdio.h>
#include <iostream.h>
#include <stdlib.h>
#include <string.h>
#include <iomanip.h>


class membership
{

struct LISTNODEPTR;

public:
membership()
~membership()

void new_membership(LISTNODEPTR *);
void display();

private:
int account_number;
char first_name[20];


};

struct listnode
{
membership member;
struct listnode *nextptr;
};


typedef struct listnode LISTNODE;
typedef LISTNODE *LISTNODEPTR;


void main()
{
int i,j,chc;

LISTNODEPTR member_list = NULL;

while(true)
{
chc = menu();

switch (chc)
{
case 1:
void new_membership(&member_list); break;

}
}

}

leeroybrown

If you're trying to create a list of Classes you might as well use OO to create the list too.

A list container and a listItem to store the object

Talliesin

template<class T> class listNode
{
T member;
listNode<T>* nextNode;
public:
/*various member functions*/
}

Then for any class (say myObj*) you can create a listnode (of class listNode<myObj*>).

This is how the STL list works, which is what you generally use for real-world code anyway, rather than creating YET ANOTHER list class for the next person to deal with the code to work out (or worse, make false assumptions about based on how he or she codes lists).

leeroybrown

Indeed, very true.

My brain was in "homework mode" ...

Programming Labs in my experience tend to require everything in first principles.

(Reinventing the wheel)

Talliesin

Of course. You shouldn't reinvent the wheel, but you should be able to reinvent the wheel!

Anyway, your wheel should use templates

leeroybrown

We're agreed

It wasn't the best piece of advice I've ever given ...