需要反转列表然后打印出来，截至目前它以相同的顺序打印列表，我一直在到处搜索，但我仍然卡住了。我什至不知道它是否正确地反转。任何帮助是极大的赞赏。
#include <string>
#include <iostream>
#include <cassert>
#include <list>
using namespace std;
class List;
class Iterator;
class Node{
public:
/**
Constructs a node with a given data value.
@param s the data to store in this node
*/
Node(string s);
private:
string data;
Node* previous;
Node* next;
friend class List;
friend class Iterator;
};
class List{
public:
/**
Constructs an empty list;
*/
List();
/**
Appends an element to the list.
@param data the value to append
*/
void push_back(string data);
/**
Inserts an element into the list.
@param iter the position before which to insert
@param s the value to append
*/
void insert(Iterator iter, string s);
/**
Reverses the order of the elements in the list.
*/
void reverse(Node *&head);
/**
Removes an element from the list.
@param iter the position to remove
@return an iterator pointing to the element after the
erased element
*/
Iterator erase(Iterator iter);
/**
Gets the beginning position of the list.
@return an iterator pointing to the beginning of the list
*/
Iterator begin();
/**
Gets the past-the-end position of the list.
@return an iterator pointing past the end of the list
*/
Iterator end();
private:
Node* first;
Node* last;
friend class Iterator;
};
class Iterator{
public:
/**
Constructs an iterator that does not point into any list.
*/
Iterator();
/**
Looks up the value at a position.
@return the value of the node to which the iterator points
*/
string get() const;
/**
Advances the iterator to the next node.
*/
void next();
/**
Moves the iterator to the previous node.
*/
void previous();
/**
Compares two iterators
@param b the iterator to compare with this iterator
@return true if this iterator and b are equal
*/
bool equals(Iterator b) const;
private:
Node* position;
List* container;
friend class List;
};
Node::Node(string s){
data = s;
previous = NULL;
next = NULL;
}
List::List(){
first = NULL;
last = NULL;
}
void List::push_back(string data){
Node* new_node = new Node(data);
if (last == NULL) // List is empty
{
first = new_node;
last = new_node;
}
else{
new_node->previous = last;
last->next = new_node;
last = new_node;
}
}
void List::insert(Iterator iter, string s){
if (iter.position == NULL) {
push_back(s);
return;
}
Node* after = iter.position;
Node* before = after->previous;
Node* new_node = new Node(s);
new_node->previous = before;
new_node->next = after;
after->previous = new_node;
if (before == NULL) // Insert at beginning
first = new_node;
else
before->next = new_node;
}
void List::reverse(Node *&head){
if((head == NULL)||(head->next=NULL))
return;
Node *top = head;
Node *tail = NULL;
Node *curr = head;
Node *temp = NULL;
while(curr != NULL){
temp = curr->next;
curr->next = curr->previous;
curr->previous = temp;
if(temp == NULL){
tail = curr;
}
curr = temp;
}
temp = head;
head = tail;
tail = temp;
}
Iterator List::erase(Iterator iter){
assert(iter.position != NULL);
Node* remove = iter.position;
Node* before = remove->previous;
Node* after = remove->next;
if (remove == first)
first = after;
else
before->next = after;
if (remove == last)
last = before;
else
after->previous = before;
delete remove;
Iterator r;
r.position = after;
r.container = this;
return r;
}
Iterator List::begin(){
Iterator iter;
iter.position = first;
iter.container = this;
return iter;
}
Iterator List::end(){
Iterator iter;
iter.position = NULL;
iter.container = this;
return iter;
}
Iterator::Iterator(){
position = NULL;
container = NULL;
}
string Iterator::get() const{
assert(position != NULL);
return position->data;
}
void Iterator::next(){
assert(position != NULL);
position = position->next;
}
void Iterator::previous(){
assert(position != container->first);
if (position == NULL)
position = container->last;
else
position = position->previous;
}
bool Iterator::equals(Iterator b) const{
return position == b.position;
}
int main(){
List staff;
// Add orginal values to staff
staff.push_back("Tom");
staff.push_back("Dick");
staff.push_back("Harry");
staff.push_back("Juliet");
Iterator pos;
// Print all values
for (pos = staff.begin(); !pos.equals(staff.end()); pos.next())
cout << pos.get() << "\n";
// Reverse the values
Node* head = NULL;
staff.reverse(head);
// Print all values to show reverse
cout << endl;
for (pos = staff.begin(); !pos.equals(staff.end()); pos.next())
cout << pos.get() << "\n";
return 0;
}