override the push() and pop(); overload the << operator for output, and add an indexing operator []

pr6.cpp

@@ -31,6 +31,7 @@ public:
     }
 
     template<class T1> friend class LinkedList;
+    template<class T1> friend class DoublyLinkedStack;
 };
 
 template<class T1>
@@ -212,13 +213,38 @@ public:
         }
         else {
             this->tail = res->getPrev();
-            this->tail->setNext(nullptr);
+            if (this->tail) {
+                this->tail->setNext(nullptr);
+            }
         }
 
         this->count--;
         return res;
     }
 
+    // Overload the << operator for output
+    friend ostream& operator<<(ostream& os, const DoublyLinkedStack& stack) {
+        DoublyLinkedElement<T>* current = static_cast<DoublyLinkedElement<T>*>(stack.head);
+        while (current != nullptr) {
+            os << current->getInfo() << " ";
+            current = static_cast<DoublyLinkedElement<T>*>(current->getNext());
+        }
+        return os;
+    }
+
+    // Overload the [] operator for indexing
+    T& operator[](int index) {
+        if (index < 0 || index >= this->count) {
+            throw out_of_range("Index out of range");
+        }
+
+        DoublyLinkedElement<T>* current = static_cast<DoublyLinkedElement<T>*>(this->head);
+        for (int i = 0; i < index; ++i) {
+            current = static_cast<DoublyLinkedElement<T>*>(current->getNext());
+        }
+        return current->info;
+    }
+
     virtual ~DoublyLinkedStack() { cout << "\nDoublyLinkedStack class destructor\n"; }
 };
 
@@ -247,6 +273,10 @@ int main() {
     doublyLinkedStack.push(20);
     doublyLinkedStack.push(30);
 
+    cout << "Stack contents: " << doublyLinkedStack << endl;
+
+    cout << "Element at index 1: " << doublyLinkedStack[1] << endl;
+
     while (!doublyLinkedStack.isEmpty()) {
         Element<int>* elem = doublyLinkedStack.pop();
         if (elem) {