I am running the following program. In this program I have to implement a doubly linked list. And I am still to complete this program. Howvever, look below at the program I have so far. I am getting an error "Unknown type name 'Node'" in the function:
template<typename T>
Node* LinkedList<T>::Find(const T& val) const {
Node *itr = nullptr;
Node *ptr = head->next;
while (ptr != tail) {
if (ptr->data == val) {
*itr = *ptr;
break;
}
ptr = ptr->next;
}
return *itr;
}
I cannot understand why I am getting that error, and what I can do to fix it?
#include <iostream>
#include <vector>
using namespace std;
template<typename T>
class LinkedList{
public:
struct Node {
T data;
Node* prev;
Node* next;
};
void PrintForward();
void PrintReverse();
void PrintForwardRecursive(const Node*);
void PrintReverseRecursive(const Node*);
int NodeCount() const;
void FindAll(vector<Node*>&, const T&);
Node* Find(const T&) const;
Node* GetNode(int& ) const;
Node* Head() const;
Node* Tail() const;
void AddHead(const T&);
void AddTail(const T&);
void AddNodesHead(const T&, int);
void AddNodesTail(const T&, int);
void InsertAfter(Node*, const T&);
void InsertBefore(Node*, const T&);
void InsertAt(const T&, int);
bool RemoveHead();
bool RemoveTail();
int Remove(const T&);
bool RemoveAt(int);
void clear();
T& operator[](int);
bool operator==(const LinkedList<T>&);
LinkedList<T>& operator=(const LinkedList<T>&);
LinkedList();
LinkedList(const LinkedList<T>&);
~LinkedList();
private:
int n;
Node* head;
Node* tail;
};
template<typename T>
void LinkedList<T>::PrintForward() {
PrintForwardRecursive(head->next);
}
template<typename T>
void LinkedList<T>::PrintReverse() {
PrintReverseRecursive(tail->prev);
}
template<typename T>
void LinkedList<T>::PrintForwardRecursive(const Node* node) {
cout << node->data << " ";
if (node->next != tail)
PrintForwardRecursive(node->next);
}
template<typename T>
void LinkedList<T>::PrintReverseRecursive(const Node* node) {
cout << node->data << " ";
if (node->next != prev)
PrintForwardRecursive(node->prev);
}
template<typename T>
int LinkedList<T>::NodeCount() const {
int num = 1;
Node *ptr = head;
while (ptr != tail) {
ptr = ptr->next;
num++;
}
return num;
}
template<typename T>
void LinkedList<T>::FindAll(vector<Node*>&matches, const T& val) {
Node *ptr = head->next;
while (ptr != tail) {
if (ptr->data == val)
matches.push_back(*ptr);
ptr = ptr->next;
}
}
template<typename T>
Node* LinkedList<T>::Find(const T& val) {
Node *itr = nullptr;
Node *ptr = head->next;
while (ptr != tail) {
if (ptr->data == val) {
*itr = *ptr;
break;
}
ptr = ptr->next;
}
return *itr;
}
template<typename T>
LinkedList<T>::LinkedList() {
head = new Node;
tail = new Node;
head->next = tail;
tail->prev = head;
n = 0;
}
template<typename T>
LinkedList<T>::~LinkedList() {
bool empty = false;
while (!empty) {
empty = RemoveHead();
}
delete head;
delete tail;
}
int main() {
std::cout << "Hello, World!" << std::endl;
return 0;
}
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