我在C ++中有关于数据结构的功课，但我遇到了一个奇怪的问题。对不起，如果标题有点不明显。首先，对于家庭作业，我们已经给出了PaperRepository类的头文件来实现。本课程通过循环双向链表保存论文信息。每篇论文都有标题，发表论文的期刊，出版年份和由另一个链表类别（排序链表）保存的共同作者列表，这是PaperRepository.h文件
// PaperRepository.h
#include <string>
#include "CDoublyLinkedList.cpp"
#include "Paper.cpp"
using std::string;
class PaperRepository
{
public:
PaperRepository();
~PaperRepository();
void addPaper( string paperTitle, string journalTitle,int publicationYear );
void removePaper( string paperTitle );
void addCoauthor( string paperTitle, string coauthorFirstName,string coauthorLastName, string coauthorInstitution);
void removeCoauthor ( string coauthorFirstName, string coauthorLastName);
void showAllPapers();
void showCoauthor( string coauthorFirstName, string coauthorLastName );
void showJournal( string journalTitle );
private:
CDoublyLinkedList<Paper> papers;
};
为了保存论文，我实施了一个循环的双向链表类（正如我的导师所说）。这是CDoublyLinkedList.cpp
// CDoublyLinkedList.cpp
#include <cstdlib>
#include <iostream>
template <class T> class CDoublyLinkedList
{
private:
struct Node
{
T data;
Node* prev,*next;
Node(const Node& other)
{
other.data = data;
other.prev = prev;
other.next = next;
}
Node(T data)
{
this->data = data;
prev = NULL;
next = NULL;
}
};
Node* head;
int listSize;
public:
CDoublyLinkedList()
{
head = NULL;
listSize = 0;
}
~CDoublyLinkedList()
{
std::cout<<"CDoublyLinked List's destructor is called."<<std::endl;
Node* cur = head;
for(int ctr = 0;ctr < listSize ; ctr++)
{
head = cur->next;
delete cur;
cur = head;
}
}
void addToBeginning(T data)
{
Node* newNode = new Node(data);
std::cout<<"inside add to beginning"<<std::endl;
if(listSize == 0)
{
newNode->next = NULL;
newNode->prev = NULL;
head = newNode;
listSize++;
return;
}
if(listSize == 1)
{
newNode->prev = head;
newNode->next = head;
head->prev = newNode;
head->next = newNode;
head = newNode;
listSize++;
return;
}
newNode->next = head;
newNode->prev = head->prev;
head->prev->next = newNode;
head->prev = newNode;
head = newNode;
listSize++;
}
void addToEnd(T data)
{
Node* newNode = new Node(data);
//newNode->data = data;
if(listSize == 0)
{
newNode->next = NULL;
newNode->prev = NULL;
head = newNode;
listSize++;
return;
}
if(listSize == 1)
{
newNode->next = head;
newNode->prev = head;
head->next = newNode;
head->prev = newNode;
listSize++;
return;
}
newNode->next = head;
newNode->prev = head->prev;
head->prev->next = newNode;
head->prev = newNode;
listSize++;
}
void add(T data)
{
std::cout<<"Inside CDoublyLinkedList add."<<std::endl;
if(listSize == 0)
{
addToBeginning(data);
std::cout<<"After adding to the beginning"<<std::endl;
}
else
addToEnd(data);
}
void clearList()
{
Node* cur = head;
for(int ctr = 0;ctr < listSize ; ctr++)
{
head = cur->next;
delete cur;
cur = head;
}
listSize = 0;
head = NULL;
}
};
这是LinkedList.cpp。由于我没有在列表中添加或删除任何共同作者，因此我不在此处编写添加和删除方法。 LinkedList.cpp
// LinkedList.cpp
#include <iostream>
#include <cstdlib>
template <class T> class LinkedList
{
private:
struct Node
{
T data;
Node *next;
Node(const Node& other)
{
other.data = data;
other.next = next;
}
Node(T data)
{
this->data = data;
next = NULL;
}
};
Node *header;
int listSize;
public:
LinkedList()
{
std::cout<<"LinkedList's constructor is called."<<std::endl;
header = NULL;
listSize = 0;
}
~LinkedList()
{
std::cout<<"Linked List destructor is called"<<std::endl;
Node* temp;
while(header)
{
temp = header;
header = header -> next;
delete temp;
}
}
我在PaperRepository类的add方法的实现在这里： PaperRepository.cpp
// PaperRepository.cpp
#include <cstdlib>
#include "PaperRepository.h"
#include <iostream>
PaperRepository::PaperRepository()
{
}
PaperRepository::~PaperRepository()
{
papers.clearList();
}
void PaperRepository::addPaper( string paperTitle, string journalTitle,int
publicationYear )
{
std::cout<<"add paper is called."<<std::endl;
Paper newPaper(paperTitle,journalTitle,publicationYear);
std::cout<<"new paper is created."<<std::endl;
std::cout<<"before adding paper."<<std::endl;
papers.add(newPaper);
std::cout<<"after adding paper."<<std::endl;
}
我没有添加其他方法，因为我的问题始于add方法。最后，我的Paper和CoAuthor类的重要部分。 Paper.cpp
// Paper.cpp
#include <string>
#include <iostream>
#include "LinkedList.cpp"
#include "CoAuthor.cpp"
using std::string;
class Paper
{
private:
string title;
string journal;
int year;
LinkedList<CoAuthor> coAuthors;
public:
Paper()
{
title = "";
journal = "";
year = 0;
}
Paper(string title, string journal, int year)
{
this->title = title;
this->journal = journal;
this->year = year;
}
~Paper()
{
coAuthors.clearList();
}
};
和CoAuthor.cpp
// CoAuthor.cpp
#include <iostream>
#include <string>
using std::string;
class CoAuthor
{
private:
string name,lastName,institution;
public:
CoAuthor(string name,string lastName, string institution)
{
this->name = name;
this->lastName = lastName;
this->institution = institution;
}
CoAuthor()
{
name = "";
lastName = "";
institution = "";
}
};
这是我正在测试的文件。 main.cpp中
// main.cpp
#include "PaperRepository.h"
#include <iostream>
#include <string>
int main()
{
PaperRepository myRep;
myRep.addPaper("MyTitle","Journal",1950);
std::cout<<"End of main..."<<std::endl;
return 0;
}
当我运行程序时，我看到在调用CDoublyLinkedList.cpp文件的add方法中的命令并执行“Node newNode = new Node（data）”时，将调用LinkedList类的析构函数。这对我来说很奇怪。另外，LinkedList类的析构函数总共被调用了5次。我将数据添加到循环双向链表类，并调用其他链表类的析构函数。对不起，这有点长，但我不能解释自己。这是main.cpp文件的输出：
>add paper is called.
> *LinkedList's constrctor is called.
> *new paper is created.
> before adding paper
> Inside Doubly Linked List's add
> LinkedList's constructor is called.
> LinkedList's destructor is called.
> inside addToBeginning.
> LinkedList's destructor is called.
> After addToBeginning method
> LinkedList's destructor is called.
> after adding paper
> LinkedList's destructor is called.
> End of main...
> Linked List's destrutor is called.
> CDoublyLinkedList's destructor is called.
答案 0 :(得分：2)
您正在为链接列表添加值，而不是指针。首先，您在堆栈上实例化（例如）一个新的Paper对象。然后，您add()到链接列表，按值传递对象，复制对象。然后函数范围结束，并且本地Paper对象被销毁。
您还有其他各种错别字和类的基本问题。例如：
struct Node{
T data;
Node *next;
Node(const Node& other){
other.data = data;
other.next = next;
}
...
}
那不应该编译。它应该是一个复制构造函数，它将成员设置为other输入参数提供的值，而不是相反。该参数为const，因此您无法对其进行修改，这就是它不应该编译的原因。
一般情况下，我建议您与教师进行简短的会谈，讨论您的代码。