我正在尝试创建一个双向链表：
class DblLinkedBag
{
private:
struct node{
string data;
node* next;
node* prev;
}*start=NULL;
int itemCount;
string item;
node *head;
node *tail;
public:
DblLinkedBag();
~DblLinkedBag();
int getCurrentSize();
bool isEmpty();
string add(string value);
bool remove(string item);
void clear();
bool contains(string target);
int getFrequencyOf();
string toVector();
string getItem();
void display();
};
到目前为止，我已经获得了add，isEmpty，getCurrentSize并且清楚地工作了。现在我只需要剩下的工作了，我很难过。我的教授给了我们一个要求，即必须按照这样的方式实施课程：
#include <iostream>
#include <string>
#include "LinkedBag.h"
using namespace std;
void displayBag(LinkedBag<string>& bag)
{
cout << "The bag contains " << bag.getCurrentSize()
<< " items:" << endl;
vector<string> bagItems = bag.toVector();
int numberOfEntries = (int) bagItems.size();
for (int i = 0; i < numberOfEntries; i++)
{
cout << bagItems[i] << " ";
} // end for
cout << endl << endl;
} // end displayBag
void copyConstructorTester()
{
LinkedBag<string> bag;
string items[] = {"zero", "one", "two", "three", "four", "five"};
for (int i = 0; i < 6; i++)
{
cout << "Adding " << items[i] << endl;
bool success = bag.add(items[i]);
if (!success)
cout << "Failed to add " << items[i] << " to the bag." << endl;
}
displayBag(bag);
LinkedBag<string> copyOfBag(bag);
cout << "Copy of bag: ";
displayBag(copyOfBag);
cout << "The copied bag: ";
displayBag(bag);
} // end copyConstructorTester
void bagTester()
{
LinkedBag<string> bag;
cout << "Testing the Link-Based Bag:" << endl;
cout << "isEmpty: returns " << bag.isEmpty()
<< "; should be 1 (true)" << endl;
displayBag(bag);
string items[] = {"one", "two", "three", "four", "five", "one"};
cout << "Add 6 items to the bag: " << endl;
for (int i = 0; i < 6; i++)
{
bag.add(items[i]);
} // end for
displayBag(bag);
cout << "isEmpty: returns " << bag.isEmpty()
<< "; should be 0 (false)" << endl;
cout << "getCurrentSize: returns " << bag.getCurrentSize()
<< "; should be 6" << endl;
cout << "Try to add another entry: add(\"extra\") returns "
<< bag.add("extra") << endl;
cout << "contains(\"three\"): returns " << bag.contains("three")
<< "; should be 1 (true)" << endl;
cout << "contains(\"ten\"): returns " << bag.contains("ten")
<< "; should be 0 (false)" << endl;
cout << "getFrequencyOf(\"one\"): returns "
<< bag.getFrequencyOf("one") << " should be 2" << endl;
cout << "remove(\"one\"): returns " << bag.remove("one")
<< "; should be 1 (true)" << endl;
cout << "getFrequencyOf(\"one\"): returns "
<< bag.getFrequencyOf("one") << " should be 1" << endl;
cout << "remove(\"one\"): returns " << bag.remove("one")
<< "; should be 1 (true)" << endl;
cout << "remove(\"one\"): returns " << bag.remove("one")
<< "; should be 0 (false)" << endl;
cout << endl;
displayBag(bag);
cout << "After clearing the bag, ";
bag.clear();
cout << "isEmpty: returns " << bag.isEmpty()
<< "; should be 1 (true)" << endl;
} // end bagTester
int main()
{
copyConstructorTester();
bagTester();
return 0;
} // end main
到目前为止，这就是我所拥有的。
#include <iostream>
#include <string>
#include <vector>
#include <stdio.h>
#include <stdlib.h>
using namespace std;
class DblLinkedBag
{
private:
struct node{
string data;
node* next;
node* prev;
}*start=NULL;
int itemCount;
string item;
node *head;
node *tail;
public:
DblLinkedBag();
~DblLinkedBag();
int getCurrentSize();
bool isEmpty();
string add(string value);
bool remove(string item);
void clear();
bool contains(string target);
int getFrequencyOf();
string toVector();
string getItem();
void display();
};
DblLinkedBag::DblLinkedBag()
{
itemCount=0;
item;
}
string DblLinkedBag::add(string value)
{
node* n;
cout<<itemCount<<endl;
if(itemCount==0)
{
n=new node;
n->data=value;
n->prev=NULL;
head=n;
tail=n;
}
if(itemCount>0 && itemCount<7)
{
n= new node;
n->data=value;
n->prev=tail;
tail->next=n;
tail=n;
}
itemCount++;
return value;
}
void DblLinkedBag::display()
{
struct node* temp=start;
while(temp != NULL)
{
cout<<temp->data<<endl;
temp=temp->next;
}
}
int DblLinkedBag::getCurrentSize()
{
return itemCount;
}
bool DblLinkedBag::contains(string target)
{
//need help here, supposed to tell if the linked list contains a certain //string
bool found= false;
node* curPtr=start;
int i=0;
while (!found && (curPtr!=NULL)&& (i<itemCount))
{
if(target==curPtr->data)
{
found=true;
}
else
{
i++;
curPtr=curPtr->next;
}
}
return found;
}
bool DblLinkedBag::isEmpty()
{
bool empty;
if (itemCount==0)
{
empty=true;
}
else
empty=false;
return empty;
}
void DblLinkedBag::clear()
{
node* nodeToDelete=start;
while (start != NULL)
{
start=start->next;
nodeToDelete->next=NULL;
delete nodeToDelete;
}
itemCount=0;
}
bool DblLinkedBag::remove(string item)
{
//need help here
}
string DblLinkedBag::toVector()
{
//need help here this is supposed to send the linked list to a vector
vector<string> vct;
node* curPtr= start;
int counter = 0;
while ((curPtr != NULL) && (counter < itemCount))
{
vct.push_back(curPtr->data);
curPtr = curPtr->next;
counter++;
}
}
int DblLinkedBag::getFrequency()
{//supposed to show how many of a certain item are in the linked list
DblLinkedBag::~DblLinkedBag()
{
}
任何帮助实现这些类函数来创建我教授给我的其他函数都会受到赞赏，我已经尝试了所有不同类型的实现，但我似乎无法弄明白。
答案 0 :(得分：-1)
首先：您的方法DblLinkedBag :: clear有错误，nodeToDelete永远不会改变（只删除第一个节点）
bool DblLinkedBag::remove(string item)
{
node* curPtr=start;
while (curPtr!=NULL)
{
if(item==curPtr->data)
{
if(curPtr->prev) curPtr->prev->next = curPtr->next;
if(curPtr->next) curPtr->next->prev = curPtr->prev;
delete curPtr;
itemCount--;
return true;
}
else
{
curPtr=curPtr->next;
}
}
return false;
}
你期望getFrequency（）做什么？