CODEWITHSUNDEEP
c++classstlstack
kelseyelayne
kelseyelayne

Reputation: 127

Using the STL stack as a member of a C++ class

I am working on a project that requires a list(singly) of stacks. I have made a class called "stacklist" that is just that, a list of stacks. I want the class to have a stack pointer that will point to the head of the list. However, I keep getting an error whenever I try to build the class.

#ifndef STACKLIST_H
#define STACKLIST_H

#include <stack>

//source: Data Structures Using C++: Linked List Implementation Part II (List Class)
//url: http://www.youtube.com/watch?feature=endscreen&NR=1&v=7vZo17iv1zQ
class stacklist
{
    public:
        stacklist();
        void addToHead(const int&);
        void printList();
        void insert(const int&);

    private:
        stack<int>* head; //THIS IS WHERE I AM HAVING THE PROBLEM
        int size;

};



#endif // STACKLIST_H

The error message is "error: expected ';' before '<' token"

Any insight that can be provided would be highly appreciated.

Upvotes: 0

Views: 493

Answers (4)

PaperBirdMaster
PaperBirdMaster

Reputation: 13320

If you're using std libraries, you must put std:: before the std object or place a using namespace std at the beggining of your source file:

#include <stack>
using namespace std; // This line brings std stuff into the current namespace.

Or:

std::stack<int>* head;

If your file is a header, it's better the first one than the second one because the using directive will be spreaded into all the files that includes StackList.h

This is no mentioned on the question, but I think is worth to say: Is quite dangerous to use pointers into classes, because you must take care of it into all constructors (default and copy) and take care on destructor too.

Revise your class dessign and think if you can use a std::stack instance instead of std::stack pointer.

Upvotes: 0

juanchopanza
juanchopanza

Reputation: 227370

The standard library stack lives in the std namespace, so you need to qualify the name appropriately:

std::stack<int>* head;

You should consider using an std::list<std::stack<int>> instead of your class.

Upvotes: 6

tozka
tozka

Reputation: 3451

Perhaps you should say std::stack

std::stack<int>* head; instead stack<int>* head;

Upvotes: 1

Kerrek SB
Kerrek SB

Reputation: 476930

The correct name of the template is std::stack.

If all you want is a list of stacks, you could always use std::list<std::stack<int>>, by the way (or std::forward_list if you only need forward traversal). But even if you pursued your own design, there's probably no reason why you can't make the stack a direct class member.

Upvotes: 5

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