Qualcuno mi può aiutare ad individuare l'errore "invalid conversion from int to node *" che mi assilla in questo programma?? Ho bisogno con urgenza per l'esame di Algoritmi e Strutture di Dati di creare una lista doppiamnete linkata di interi, ma proprio non ci riesco. Ogni aiuto è graditissimo. Grazie mille.


#include <iostream.h>

class node { // A simple class
protected:
int number; // Value stored in the node
node *next; // Pointer to next node
node *prev; // Pointer to previous node

public:
node() { next = NULL; prev = NULL; } // With a constructor
void insertBefore(int number, node *nodeB); // Seven methods
void insertAfter(int number, node *nodeA);
void removeBefore(node *nodeB);
void removeAfter(node *nodeA);
void removeNode(node *newNode);
void printDListFront();
void printDListBack();
~node(); // and a destructor
};


// This function inserts a node before nodeB
void node::insertBefore(int number, node *nodeB)
{
node *newNode;
newNode = new node;
newNode->prev = nodeB->prev;
newNode->next = nodeB;
newNode->number = number;

if (nodeB->prev == NULL) {
this->next = newNode;
}
nodeB->prev = newNode;
removeNode(newNode);
}

// Inserts a node after nodeB
void node::insertAfter(int number, node *nodeA)
{
node *newNode;
node *nodeB;
newNode = new node;
newNode->next = nodeB->next;
newNode->prev = nodeB;
newNode->number = number;

if (nodeB->next == NULL) {
cout << "Enter a digit : \n";
cin >> number;
this->prev = newNode;
}
nodeB->next = newNode;
}

// Removes before a node
void node::removeBefore(node *nodeB)
{
if (nodeB->prev == this->next) {
this->next = nodeB;
this->next->prev = NULL;
} else {
removeNode(nodeB->prev);
}
}

// Removes after a node
void node::removeAfter(node *nodeA)
{
if(nodeA->next == this->prev) {
this->prev = nodeA;
this->prev->next = NULL;
} else {
removeNode(nodeA->next);
}
}

// Removes a particular node
void node::removeNode(node *nodeToRemove)
{
if (nodeToRemove == this->next) {
this->next;
this->next->prev = NULL;
} else if (nodeToRemove == this->prev) {
this->prev;
this->prev->next = NULL;
} else {
nodeToRemove->prev->next = nodeToRemove->next;
nodeToRemove->next->prev = nodeToRemove->prev;
}
}

// Prints out the doubly linked list from front
void node:rintDListFront()
{
node* temp;
temp = this->next;
cout << "--------------------------------\n";
cout << "List from front : \n";
cout << "--------------------------------\n";

while (temp != NULL) {
cout << "|" << temp->number << "|";
temp = temp->next;
}
cout << "\n\n";
}

// Prints out the doubly linked list from backwards
void node:rintDListBack()
{
node* temp;
temp = this->prev;
cout << "--------------------------------\n";
cout << "List from backwards : \n";
cout << "--------------------------------\n";

while (temp != NULL) {
cout << "|" << temp->number << "|";
temp = temp->prev;
}
cout << "\n\n";
}


int main()
{
node *llista;
int num, NodeA, NodeB, NewNode;
int choice;
llista->node();

switch (choice) {
cout << "Enter 1 to insert a node before in the list; 2 to insert a node after; 3 to remove a node before; 4 to \n";
cout << "remove a node after; 5 to remove any node; 6 to print out the doubly linked list frontally; 7 to print \n";
cout << "out the doubly linked list from backwards; 0 to exit.\n\n";
cout << "Please enter your choice by number : \n";
cin >> choice;

case 1 :
llista->insertBefore(num, NodeB);
break;

case 2 :
llista->insertAfter(num, NodeA);
break;

case 3 :
llista->removeBefore(NodeB);
break;

case 4 :
llista->removeAfter(NodeA);
break;

case 5 :
llista->removeNode(NewNode);
break;

case 6 :
llista->printDListFront();
break;

case 7 :
llista->printDListBack();
break;

case 0 :
cout << "Exiting program!\n\n";
break;

default :
cout << "Sorry! Bad menu selection!\n\n";
break;
}

system("pause");
return 0;
}