Question

Hi I ran my program through valgrind and this is the report

Heap Summary:
in use at exit: 8 bytes in 1 blocks
total heap usag: 1 allocs, 0 frees, 8 bytes allocated
Leak Summary:
definitely lost: 8 bytes in 1 blocks

This is my program

int main() {    
NodeData nodedata1(1, 'a');
List list1;
list1.insert(&nodedata1);

   return 0;
}
//---my List class
class List {
public:
   List(); 
   bool insert(NodeData*);                     // insert one Node into list
   bool isEmpty() const; 
private:
   struct Node {              // the node in a linked list
      NodeData* data;         // pointer to actual data, operations in NodeData
      Node* next;
   };
   Node* head;                                 // pointer to first node in list
};
// my bool insert method
bool List::insert(NodeData* rightPtr) {  
   Node* newPtr = new Node;
   newPtr->data = rightPtr;    
   if (isEmpty() || *newPtr->data < *head->data) {
      newPtr->next = head;                           
      head = newPtr;
   }
   else {
      Node* current = head; 
      while (current->next !=NULL && *current->next->data < *newPtr->data) {
           current = current->next;
      }
      newPtr->next = current->next;
      current->next = newPtr;
   }
   return true;
}

Answer 1

You are dynamically allocating a Node in the insert method and never deleting it:

Node* newPtr = new Node;

You need to keep track of these Nodes and delete them in the List destructor, or have some other arrangement to handle the memory (i.e. pass the ownership of the Nodes to something that is in charge of deleting them at the right moment).