Stack accessible by all member functions of a class

Question

I want all member functions of a class to have access to the same stack. Each member function will push data to the stack and pop data from the stack.

I am having a hard time declaring the stack. I have a cpp file and a header file it won't let me declare a stack in the header file. Does anyone have an example of how this could be done?

I need to use a stack as a LIFO data structure makes more sense as I only need to access the last item placed on the stack.

I tried declaring it in the header file as a protected member with stack<int> items; but get a compile error "stack does not name a type".

Adam

Answer 1

Don't pass around basic data structures.

Your stack represents something, maybe a stack of Orders in a sandwich shop, or a stack of Pancakes being rendered in glorious 5D. Create an object of type Pancakes, or Orders as appropriate, and pass a reference to objects that need to know about it.

// pancakes.h
#include <stack>    
class Pancake;

class Pancakes
{
public:
    void addPancake(const Pancake& pancake);
    Pancake& top() const;
    void pop();
private:
    std::stack<Pancake> m_pancakes;
};

// pancakes.cpp
#include "pancakes.h"
#include "pancake.h"

void Pancakes::addPancake(const Pancake& pancake)
{
    m_pancakes.push(pancake);
}

Pancake& Pancakes::top() const
{
    return m_pancakes.top();
}

void Pancakes::pop()
{
    m_pancakes.pop();
}

Answer 2

Ok, let's assume you're using a std::stack.

class MyClass
{
private:
    std::stack<int>& myStack_;
public:

    MyClass(std::stack<int>& stack) : myStack_(stack) { };
}; // eo MyClass

Just pass a reference to the stack each time you make an instance of MyClass. This also avoids singletons:

std::stack<int> globalStack;
MyClass class1(globalStack);
MyClass class2(globalStack);

Answer 3

Be sure you do a

#include <stack>

and additionally either do a

using namespace std;

or a

std::stack<int> items;

in the header file.