Overloading Operator << Linked List

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Hello, I am trying to overload the oprator "<<", but I dont know what i am doing wrong, if someone can help me please, I will be grateful.

This is my overloading declaration, each part:
friend ostream &operator<<( ostream&, const OrderedList& );

OrderedList::node* OrderedList::search(int value){
    node *p = new node;
    p = first;
    while(p != NULL){
            if(p->data == value){
                       cout <<"here";
                       return p->link;
                       }
            p = p ->link;
            }
    cout << "The element searched has not been found." << endl;
    
    }

#include <iostream>

using namespace std;

class OrderedList{
      friend ostream &operator<<( ostream&, const OrderedList& );
      
      private:
              struct node{
                     int data;
                     node *link;
                     };
              node *first, *last;
              int count;
      public:
             OrderedList();
             ~OrderedList();
             void insert(int);
             void display();
             int remove(int);
             node* search(int);
             //<<
      
};

OrderedList::OrderedList(){
                           
                           first = NULL;

}

OrderedList::~OrderedList(){
                            while(first != NULL){
                                      node *destruct;
                                      destruct = first;
                                      first = first -> link;
                                      delete destruct;
                            }
                            delete first;
                            cout << "Destructor called";                        
}

void OrderedList::insert(int value){

                    node *NewNode = new node;
                    NewNode -> data = value;
                    NewNode -> link = NULL;
                    
                    node *p = new node;
                    p = first;
                    
                    node *before = p;

                    if(first == NULL){
                            first = NewNode;
                                 }
                    else{
                         while(p != NULL){
                                 
                                 if(value < first->data){
                                            NewNode -> link = first;
                                            first = NewNode;
                                            break;
                                            }
                                 else if(p -> data >= value){
                                      NewNode -> link = before -> link;
                                      before -> link = NewNode;
                                      break;
                                      }
                                      before = p;
                                      p = p -> link;
                                 if(p == NULL){
                                      before -> link = NewNode;
                                      }
                                 }
                         
                         
                         }
}
void OrderedList::display(){
     node *p = new node;
     p = first;
          while(p != NULL){
                  cout << p -> data << " ";
                  p = p -> link;
                  }
          cout << endl;
}

int OrderedList::remove(int value){
    node *p = new node;
    p = first;
    node *before = p;
    while(p != NULL){
            if(first->data == value){
                           before = first;
                           first = first ->link;
                           delete before;
                           break;
                           return 0;
                           }
            before = p;
            p= p->link;
            if(p->data == value){
                       before->link = p->link;
                       delete p;
                       break;
                       return 0;
                       }
            
            }
    return -1;
}

OrderedList::node* OrderedList::search(int value){
    node *p = new node;
    p = first;
    while(p != NULL){
            if(p->data == value){
                       cout <<"here";
                       return p->link;
                       }
            p = p ->link;
            }
    cout << "The element searched has not been found." << endl;
    
    }

OrderedList::ostream &operator<<( ostream &output, const OrderedList& Olist){
        node *p;
        for(p = Olist; p != 0; p = p -> link){
              output << p -> data << endl;
}
        
        return output;
}
        

int main(){
    OrderedList list;
    list.insert(-1);
    list.insert(7);
    list.insert(2);
    list.insert(1);
    list.insert(6);
    list.insert(-9);
    
    list.display();
    list.remove(7);
    list.remove(-9);
    list.remove(1);
    
    cout << endl << list.search(7);
    
    cout << list;
    
    system("pause");
    return 0;
    }

[MiiNiPaa]

OrderedList::ostream &operator<<( ostream &output, const OrderedList& Olist){

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MiiNiPaa,
If I do what you are telling me, this is what happens, I get this errors:

In function `std::ostream& operator<<(std::ostream&, const OrderedList&)':
`node' undeclared (first use this function)

(Each undeclared identifier is reported only once for each function it appears in.)

`p' undeclared (first use this function)

`Olist' undeclared (first use this function)

[MiiNiPaa]

Use qualified names:
OrderedList::node* p;

Also for(p = Olist; p != 0; p = p -> link){ should probable be for(p = Olist.first; p != 0; p = p -> link){

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YES IT WORKS!!!

THANKS YOU VERY MUCH MiiNiPaa!!