打印功能-链表c ++

Question

I am trying to figure out what I am doing wrong with this printList Function. I am getting the following compiler error:

No operator "<<" matches these operands.

The function is as follows:

void printList(const List& theList)
{   
for(Node* i = theList.getFirst(); i != theList.getLast(); ++i)
{
    cout << *i << " ";
    cout << endl;
}
}

I have the following as well,

#include "List.h"
#include <iostream>

I am thinking my print function is just way off base. Can anyone point me in the right direction?

Here are my classes, I don't have a List::Iterator. What would you suggest?

class List
{
private:
    int nodeListTotal;
    Node* first;
    Node* last;

public:
    //Constructor
    List();

    void push_back(Node*);
    void push_front(Node*);
    Node* pop_back();
    Node* pop_front();
    Node* getFirst() const;
    Node* getLast() const;
    int getListLength() const;
    void retrieve(int index, int& dataItem) const;
};

class Node
{
private:
    string dataItem;
    string dataUnit;
    int unitTotal;
    Node* next;

public:
    //Constructor
    Node();

    Node(int, string, string);

    string getDescription( );
    void setDescription(string);

    string getQuantityName();
    void setQuantityName(string);

    int getQuantityNumber();
    void setQuantityNumber(int);

    Node* getNext( );
    void setNext(Node*);
};

Answer 1

You need to overload operator<< for Node type:

std::ostream& operator<<(std:::ostream& os, const Node& node)
{
    os << node.getQuantityName() << " " << node.getDescription();
    return os;
}

Answer 2

As the error message says

No operator "<<" matches these operands.

you don't have the << operator defined for your class.

Answer 3

In your printList() function, replace cout << *i << " "; with
cout << i->getDescription() << endl;