I have a linked list that contains a pointer to the first and last node and size which indicates how many nodes are there in the list.
I have a function that returns the first node.
I want to be able to change the m_data in the first node using queue1.front() = 3;. However, I am getting
invalid conversion from ‘int’ to ‘Node<int>*’
error while compiling
template <class T>
class Node {
public:
Node(const T& t);
~Node() = default; // Destructor
Node(const Node&) = default; // Copy Constructor set to default
Node& operator=(const Node&) =
default; // Assignment operator set to default
T& getData();
const T& getData() const;
Node* getNext();
void setNext(Node<T>* newNext);
private:
T m_data;
Node* m_nextNode;
};
template <class T>
Node<T>::Node(const T& t) {
this->m_data = t;
this->m_nextNode = nullptr;
}
template <class T>
class Queue {
public:
static const int SIZE_EMPTY = 0;
Queue();
~Queue(); // Destructor
Queue(const Queue&) = default; // Copy Constructor set to default
Queue& operator=(const Queue&) =
default; // Assignment operator set to default
void pushBack(const T& t);
Node<T>*& front();
const Node<T>*& front() const;
void popFront();
int size() const;
class EmptyQueue {};
private:
Node<T>* m_head;
Node<T>* m_tail;
int m_size;
};
template <class T>
Node<T>*& Queue<T>::front() {
if (this->m_size == Queue<T>::SIZE_EMPTY) {
throw Queue<T>::EmptyQueue();
}
return this->m_head;
}
template <class T>
void Queue<T>::pushBack(const T& t) {
this->m_size += 1;
Node<T>* newNode = new Node<T>(t);
this->m_tail = newNode;
if (this->m_size == 1) {
this->m_head = newNode;
} else {
Node<T>* tempNode = this->m_head;
while (tempNode->getNext()) {
tempNode = tempNode->getNext();
}
tempNode->setNext(newNode);
}
}
int main() {
Queue<int> queue1;
queue1.pushBack(1);
queue1.front() = 3;
}
>Solution :
Queue<T>::front() is returning a Node<T>*& when it should return a T&.
Example:
template <class T>
T& Queue<T>::front() {
if (this->m_size == Queue<T>::SIZE_EMPTY) {
throw Queue<T>::EmptyQueue();
}
return m_head->getData();
}
template <class T>
const T& Queue<T>::front() const {
if (this->m_size == Queue<T>::SIZE_EMPTY) {
throw Queue<T>::EmptyQueue();
}
return m_head->getData();
}
You also need to make the same change in the class definition:
template <class T>
class Queue {
public:
//...
T& front();
const T& front() const;
//...
};