Add the operatiions save and restore to the pointer based implementation of the

Question

Add the operatiions save and restore to the pointer based implementation of the ADT list. These operations use a file to save and restore the list items. Help is greatly appreciative.

Explanation / Answer

///Storing is nothing but inserting and restoring is retieving in the following code #include "list.h" // header file #include #include List::List(): size(0), head(NULL) { } // end default constructor List::List(const List& aList) : size(aList.size) { if(aList.head == NULL) head = NULL; else{ head = new ListNode; head->item = aList.head->item; ListNode *newPtr = head; for(ListNode *origPtr = aList.head->next; origPtr != NULL; origPtr = origPtr->next){ newPtr->next = new ListNode; newPtr = newPtr->next; newPtr->item = origPtr->item; } newPtr->next = NULL; } } List::~List(){ while (!isEmpty()) remove(1); } bool List::isEmpty() const { return size == 0; } // end isEmpty int List::getLength() const { return size; } // end getLength List::ListNode *List::find(int index) const { if((index < 1) || (index > getLength())){ return NULL; } else{ ListNode *cur = head; for (int skipper = 1; skipper next; return cur; } } } void List::retrieve(int index, ListItemType& dataItem) const throw (ListIndexOutOfRangeException) { if ( (index getLength())){ throw ListIndexOutOfRangeException( "ListIndexOutOfRangeException:retrieve index out of range"); }else{ ListNode *cur = find(index); dataItem = cur->item; } } void List::insert(int index, const ListItemType& newItem) throw(ListIndexOutOfRangeException, ListException) { int newLength = getLength() + 1; if((index < 1) || (index > newLength)){ throw ListIndexOutOfRangeException( "ListIndexOutOfRangeException:retrieve index out of range"); }else{ try { ListNode *newPtr = new ListNode; size = newLength; newPtr->item = newItem; if(index == 1){ newPtr->next = head; head = newPtr; }else{ ListNode *prev = find(index - 1); newPtr->next = prev->next; prev->next = newPtr; } } catch (bad_alloc e) { throw ListException("ListException: insert cannot allocate enough memory."); } } } void List::remove(int index) throw (ListIndexOutOfRangeException) { ListNode *cur; if( (index getLength())){ throw ListIndexOutOfRangeException( "ListIndexOutOfRangeException: remove index out of range"); }else{ --size; if(index == 1){ cur = head; head = head->next; }else{ ListNode *prev = find(index-1); cur = prev->next; prev->next = cur->next; } cur->next = NULL; delete cur; cur = NULL; } }

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