CODEWITHSUNDEEP
c++c++11gcc
ceaston7
ceaston7

Reputation: 67

"is private within this context" is being thrown for function which should not be private (GCC 5.3.0, C++11)

I am attempting to create a queue, which requires the creation of another object stored in the queue. The errors are

binary.cpp: In function ‘int main()’:
binary.cpp:183:1: error: ‘Queue<T>::Queue(T) [with T = binary<std::basic_string<char> >*]’ is private
 Queue<T>::Queue(T item){
 ^
binary.cpp:286:65: error: within this context
  Queue<binary<string>*>* queue = new Queue<binary<string>*>(tree);
                                                                 ^

and 

binary.cpp: In instantiation of ‘Queue<T>::Queue(T) [with T = binary<std::basic_string<char> >*]’:
binary.cpp:286:65:   required from here
binary.cpp:132:1: error: ‘Link<T>::Link(T) [with T = binary<std::basic_string<char> >*]’ is private
 Link<T>::Link(T item){
 ^
binary.cpp:184:7: error: within this context
  head = new Link<T>(item);

The first is the instantiation of the Queue, and the second comes from the Queue's constructor, which is called in the instantiation line in the first error. The important declarations and definitions are:

template<class T>
class Link{
    Link(T item);

    private:
    T content;
    Link<T>* next;
};

template<class T>
Link<T>::Link(T item){
    content = item;
    next = NULL;
}

template<class T>
class Queue{
    Queue();
    Queue(T item);

    private:
    Link<T>* head;
    Link<T>* end;
    int length;
};

template<class T>
Queue<T>::Queue(T item){
    head = new Link<T>(item);
    end = head;
    length = 1;
}

The Link class is declared and defined before the Queue class, and both are declared and defined before they are used in code. Thank you for your time.

Upvotes: 4

Views: 21957

Answers (1)

Angelus Mortis
Angelus Mortis

Reputation: 1554

By default class members are private, even you use private access specifier later, Your code is like :

template<class T>
class Queue{
    Queue(); //Implicitly private
    Queue(T item); //Implicitly private

    private: //explicit private
    Link<T>* head;
    Link<T>* end;
    int length;
};

so you need to make constructors public :

template<class T>
class Queue{
    public:
    Queue(); 
    Queue(T item);
    private:
    Link<T>* head;
    Link<T>* end;
    int length;
};

Same goes for Link<T> class template.

Upvotes: 7

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