Is this possible?

[AndroidZ]

I need a global function: void print_stack( Stack const* pstack );
to print out each element of a list. It needs to access private members. Can it be a friend AND global?

What do I need to make it a friend of if I do?

node.h

#ifndef NODE_H
#define NODE_H

// The node class for singly-linked list of integers

#include <cassert>
#include <iostream>
using namespace std;

class Node
{
    //friend void print_list( Node const& head );
public:
    Node* pnext;
    int data;

    // Constructor taking initial value:
    Node( int value = 0 )
    : pnext( NULL ), data( value )
    {
    }

    // Copy constructor:
    Node( Node const& other )
    : pnext( NULL ), data( other.data )
    {
    }

    // Insert new node in front:
    void insert( Node* newNode )
    {
        newNode->pnext = pnext;
        pnext = newNode;
    }

    // Remove node in front:
    void remove_next()
    {
        if ( pnext == NULL ) return;
        Node* obsolete = pnext;
        this->pnext = obsolete->pnext;
        // Make node "single":
        obsolete->pnext = NULL;
    }

    // Remove other node in front:
    bool remove( Node* other )
    {
        Node* previous = this;
        Node* iter = pnext;
        while ( iter != other ) {
            if ( iter == NULL )
                return false;
            previous = iter;
            iter = iter->pnext;
        }
        previous->pnext = iter->pnext;
        // Make node "single" after successful removal:
        other->pnext = NULL;
        return true;
    }

    // Measure distance to other node:
    int distance( Node const* other ) const
    {
        int hops = 1;
        Node const* iter = pnext;
        while ( iter != other ) {
            if ( iter == NULL ) {
                // Don't count this last hop:
                return hops - 1;
            }
            iter = iter->pnext;
            ++hops;
        }
        return hops;
    }
    // Calculate number of nodes in the list:
    size_t size() const
    {
        return distance( NULL );
    }
};

//void print_list( Node const& head );
#endif //NODE_H 

stack.h

#if (!defined(STACK_H))
#define STACK_H
#include "node.h"

class Stack {
	Node head;
public:

    // Push new element to the stack:
    void push( int value );

    // Pop element from the stack:
    int pop();

    // Writeable access to element on top of the stack:
    int& top();

    // Read-only access to element on top of the stack:
    int top() const;

    // Return stack size:
    size_t size() const;

    // Is stack empty?
    bool is_empty() const;

    friend void print_stack( Stack const* pstack );

};
#endif 

stack.cpp

#include "node.h"
#include "stack.h"

using namespace std;


void Stack::push(int n){
	//Node * ptemp = new Node(value);
    //head.insert(Node(value))
	head.insert(new Node(n));
}

int Stack::pop(){
	Node* ptr_obsolete_node = head.pnext;
    head.remove_next();
	delete ptr_obsolete_node;
}

int& Stack::top(){
    return head.pnext->data;
}

int Stack::top() const{
    return head.pnext->data;
}

size_t Stack::size() const{
  return head.size() - 1;
}

bool Stack::is_empty() const{
  return size() == 0;
}

main

#include <cassert>

#include "Node.h"
#include "Stack.h"

//void print_stack( Stack const* pstack );
int main()
{
    Stack st;
    assert( st.size() == 0 );

    st.push( 123 );
    assert( st.size() == 1 );
    assert( st.top() == 123 );

    st.top() = 321;
    assert( st.size() == 1 );
    assert( st.top() == 321 );

    st.push( 456 );
    assert( st.size() == 2 );
    assert( st.top() == 456 );

    print_stack(&st);

    st.top() = 654;
    assert( st.size() == 2 );
    assert( st.top() == 654 );

    st.pop();
    assert( st.size() == 1 );
    assert( st.top() == 321 );

    st.pop();
    assert( st.size() == 0 );

    return 0;
}

  Stack print_stack( Stack const* pstack ){
    for (;pstack->head;){
    }

}

[ascii]

Yes, you can have global functions be a friend function to a class.

[AndroidZ]

Where would I declare and define it? What I currently have gives me an error. Would I make it a friend of stack in this case?

[ascii]

Try something like this:

class A {
public:
	A(): a(6) 
	{ }
	friend int setA(int x);	
private:
	int a;
}

int setA(A &x)
{
	A.a = 5;
}

[AndroidZ]

If I do that in my stack class, will that allow me to print the stack by accessing members of the node class with a global print function? I doubt I'm going to figure this out before midnight, which is when this is due.

[AndroidZ]

Or can I use that to set an int to whatever value is on top of the stack and then print that int? In this case, how the hell do I loop through the stack?

My understanding of pointers, addresses, and dereferencing is still shaky.

What are you doing on line 3 exactly?

[LB]

class Stack
{
    friend void print_stack( Stack const* pstack );
};

[AndroidZ]

when I try this:

void print_stack( Stack const* pstack ){
    for (;pstack.head.pnext.data != NULL;){
            std::cout << "inloop";
    }

}

I get the error:
request for member 'head' in 'pstack', which is of non-class type 'const Stack*'|

[ascii]

You need (well should, it looks a lot cleaner than the alternative) to use the arrow -> operator when dereferencing a pointer to a class method or member.

[AndroidZ]

I still can't figure this damned thing out. I need to access data. For which dot operators do I use the arrow?

F:\cis255\list\stack.cpp|36|error: request for member 'head' in 'pstack', which is of non-class type 'const Stack*'|

[AndroidZ]

got it with this:
pstack->head.pnext->data
Now I just have to figure out, in the next ten minutes, how to loop through them.