Overloading comparison operators for stacks

Question

I need some help here: I'm asked to do some overloading to comparison operators of 2 stacks. I have the syntax figured out, I'm just having trouble writing the definition. So please help me.

At least to one operator overload and then I will do it for the rest.

struct linklist
{
    int no;
    struct linklist *next;
};

class Stack
{
private:
    linklist *list,*head;

public://constructor and destructor
    Stack();
    ~Stack();
public:// main functions
    void push();
    void show();
    void pop();

public://overloaded operations

    friend bool operator == (const Stack &stack1, const Stack &stack2);
    friend bool operator != (const Stack &stack1, const Stack &stack2);
    friend bool operator < (const Stack &stack1, const Stack &stack2);
    friend bool operator > (const Stack &stack1, const Stack &stack2);

};

Answer 1

It really depends on what you actually want to compare. Is it identity of stacks or just number of elements on stacks? Since you want to define smaller and greater operators, I assume you want to compare the number of elements in the stacks.

The equal operator would be like this:

bool operator==( const Stack &stack1, const Stack &stack2)
{
  return stack1.list->no == stack2.list->no;
}

Of course you need to consider cases where the list member of a Stack object is NULL.