Question

我有一个链表类，它使用Node类和List类的模板。我做了一些调试，得出的结论是在我的Node类中，成员函数不能访问成员数据，但构造函数可以。我想知道如何解决这个问题！

#include <iostream>
#include <fstream>
#include <string>
#include "List.h"


using namespace std;


int main()
{
ifstream fileIn("data1.txt");

List<int> studentList;

if(fileIn.fail())
    cout << "file did not open" << endl;
else

    studentList.add(fileIn);




fileIn.close();
cin.get();
cin.ignore();
return 0;

}

// List.h //忽略评论的方法，还没有写出来。

#ifndef LIST_H
#define LIST_H

#include <cstdlib>
#include <iostream>
#include <fstream>
#include "Node.h"

using namespace std;

template <class NumType>
class List
{  

int counter;

bool isEmpty();
const bool print(){
}

public:

Node<NumType> * head;

    List()
    {

        this->head = NULL;
        counter = 0;
    }

    ~List()
    {

    }


    //place in an order thart keeps the array in ascending order
    void add(ifstream &);
/*  
    Node* location(Node *){
    }

    bool remove(const int){
    }

    bool clear(){
    }

    const void peek(const Node*){
    }

    //average of all test scores or just one students test scores?
    float average(){
    }

    char grade(){
    }
*/
};



#include "List.cpp"
#endif

// List.cpp

#include "List.h"


using namespace std;

template <class NumType>
bool List<NumType> :: isEmpty()
{
cout << "inside isEmpty" << endl;
return(head == NULL);
}


template <class NumType>
void List<NumType> :: add(ifstream & fin)
{   int dummyID;
NumType tests[3];
string dummyName;


while(fin >> dummyID)
{       fin.ignore();
        getline(fin, dummyName);

        for(int x = 0; x < 3; x++)
            fin >> tests[x];
        fin.ignore();

        cout << dummyID << endl;
        cout <<dummyName << endl;
        for(int y = 0; y < 3; y++)
            cout << tests[y] << " ";

    if(isEmpty())
    {   

        this->head = new Node<NumType>(NULL, tests, dummyID, dummyName);
        counter++;cout << "inside" << endl;
    }
    else 
    {
        Node<NumType> *newNode = new Node<NumType>(NULL, tests, dummyID,    dummyName);



        Node<NumType> *first = new Node<NumType>(NULL, tests, dummyID, dummyName);
        Node<NumType> *second;

        first = this->head;
        second = this->head->getNext();

        //create location() method to handle this!
        for(int x = 0; x < counter; x++)
        {           

                if(first->getID() > newNode->getID())
                {
                    head = newNode;

                    counter++;
                    break;  
                }
                else if(first->getID() < newNode->getID() && second->getID() > newNode->getID())
                {

                    newNode->setNext(second);
                    first->setNext(newNode);

                    counter++;
                    break;
                }
                else if(second->getID() < newNode->getID() && second->getNext() == NULL)
                {
                    second->setNext(newNode);

                    counter++;
                    break; 
                }
                else
                {
                    first = second;
                    second = second->getNext();
                }
        }

    }
}
Node<NumType> * temp = head;
for(int x = 0; x <= counter; x++)
{
    NumType *arr;

    cout << temp->getID() << endl << temp->getName() << endl;
    arr = temp->getAllScores();
    for(int y = 0; y <3 ; y++)
        cout << *(arr+y) << endl;

    temp = temp->getNext();
}

}

// Node.h

#ifndef NODE_H
#define NODE_H


#include <cstdlib>
#include <iostream>

using namespace std;

template <class ItemType>
class Node
{

    static const int SIZE = 3;
    int ID;
    ItemType scores[SIZE];
    string name;
    Node *next;



public:

    Node()
    {
        this->scores[0] = 0;
        this->scores[1] = 0;
        this->scores[2] = 0;
        this->name = "";
        this->ID = 0;
        this->next = NULL;  
    }


    Node(Node * nPtr, ItemType tests[], int num, string n)
    {
        this->next = nPtr;

        for(int z = 0; z < SIZE; z++)
            this->scores[z] = tests[z];

        this->ID = num;
        this->name = n;
    }

    ~Node(){}


    void setNext( Node * );

    string getName();

    int getID();


    ItemType* getAllScores();

    Node* getNext();




};

#include "Node.cpp"
#endif

Node.cpp

#include "Node.h"
#include <string>

using namespace std;


template <class ItemType>
void Node<ItemType> :: setNext( Node * nextPtr)
    {
        cout << "inside setNext()" << endl;
        this->next = nextPtr;
        cout << "exited setNext()" << endl;
    }

    template <class ItemType>
    string Node<ItemType> :: getName()
    {
        return (this->name);
    }

    template <class ItemType>
    int Node<ItemType> :: getID()
    {
        return (this->ID);  
    }

    template <class ItemType>
    ItemType* Node<ItemType> :: getAllScores()
    {
        return (this->scores);
    }

    template <class ItemType>
    Node<ItemType> * Node<ItemType> :: getNext()
    {
        return (this->next);
    }

Answer 1

我想我发现了错误。第一次运行add方法头设置，但第二次尝试设置第二个值。你有这个代码

first = this->head;// this is the first element
second = this->head->getNext(); // this is null (hast been assign yet

然后你进入for循环，在第一个＆＃34;否则如果＆＃34;声明你有这个：

else if(first->getID() < newNode->getID() && second->getID() > newNode->getID())

当你说第二个＆gt; getID（）时，你说null-＆gt; getID（）会导致分段错误。

我希望这可以解决您的问题。祝你好运！

类链接列表模板运行时错误

1 个答案: