//is there a more efficient way to write out these functions in c++ ? without using include

//Looking at the methods I have, can you show me a different way of doing it.

//Like can you do ListItr itr1.current=head->next; all in one line?

//note: the list holds integers. there must be a List Itr and Listnode (i've copy the code from the list itr file so you can get a better understanding)

// List c plus plus file

void List::makeEmpty(){ ListNode *temp=head->next; while(temp!=tail){ temp=temp->next; delete temp->previous; temp->next=temp->next; temp->previous->next=temp->next; } count=0; }

ListItr List::first(){ ListItr itr1; itr1.current=head->next; return itr1; }

ListItr List::last(){ ListItr itr1; itr1.current=tail->previous; return itr1; }

void List::insertAfter(int x, ListItr position){ ListNode *pos=position.current; ListNode *newNode=new ListNode; ListNode *nextNode=pos->next; newNode->next=nextNode; newNode->previous=pos; newNode->value=x; pos->next=newNode; nextNode->previous=newNode; count++; }

void List::insertBefore(int x, ListItr position){ ListNode *pos=position.current; ListNode *newNode=new ListNode; ListNode *prevNode=pos->previous; newNode->next=pos; newNode->previous=prevNode; newNode->value=x; prevNode->next=newNode; pos->previous=newNode; count++; }

void List::insertAtTail(int x){ ListNode *newNode=new ListNode; ListNode *prevNode=tail->previous; newNode->next=tail; newNode->value=x; prevNode->next=newNode; tail->previous=newNode; newNode->previous=prevNode; count++; }

void List::remove(int x){ ListItr itr1=find(x); ListNode *pos=itr1.current; ListNode *prevNode=pos->previous; ListNode *nextNode=pos->next; prevNode->next=nextNode; nextNode->previous=prevNode; count--; }

ListItr List::find(int x){ ListItr itr1=first(); while(!itr1.isPastEnd()){ if(itr1.current->value==x){ return itr1;} else{ itr1.moveForward(); } } return itr1; }

int List::size() const{ return count; }

void printList(List& theList, bool forward){ ListItr itr1=theList.first(); ListItr itr2=theList.last(); if (forward){ while(!itr1.isPastEnd()){ cout << itr1.retrieve(); itr1.moveForward();} } else{ while(!itr2.isPastBeginning()){ cout << itr2.retrieve(); itr2.moveBackward();}} }

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// This is the List iterator c plus plus file #include #include #include #include #include "ListItr.h" using namespace std;

//constructor ListItr::ListItr(){ current=new ListNode(); }

// One parameter constructor ListItr::ListItr(ListNode* theNode){ current=theNode; }

//returns if the itr is past the end bool ListItr::isPastEnd() const{ return (current->next==NULL); }

//returns if the itr is past the beginning bool ListItr::isPastBeginning() const{ return (current->previous==NULL); }

//moves the itr forward void ListItr::moveForward(){ if(this->isPastEnd()!=true){ current=current->next; }}

//moves the itr backwards void ListItr::moveBackward(){ if(this->isPastBeginning()!=true){ current=current->previous;} }

//returns value at the itr's current node int ListItr::retrieve() const{ return current->value; }