Question

我的老师要求写一个模板类列表（就像在STL中一样）我的代码编译但它会崩溃，但我找不到原因，有人可以试着帮我吗？我想可能有两个参数的构造函数有问题吗？

-----Main.cpp------
#include "Liste.h"
#include <iostream>

int main()
{
    Liste<int> l ;
    int x = 5 ;
    int y = 6 ;
    int z = 7 ;
    l.insert_first(y) ;
    l.insert_first(x) ;
    l.insert_last(z) ;
    std::cout << l << std::endl ;
}

-----Liste.h------
#pragma once
#include <stdio.h>
#include <iostream>
#include "NoeudListe.h"

template <class T> class Liste
{

private:
    NoeudListe<T>* tete;
    NoeudListe<T>* fin;

public:

    Liste()
    {
        tete = new NoeudListe<T>(NULL,fin,NULL);   //<-----I think the problem lies here beacause the val can`t be NULL? But I tried 0, still not work...
        fin  = new NoeudListe<T>(tete,NULL,NULL);
    }

    void insert_after (T& val, NoeudListe<T>* location)
    {
        NoeudListe<T>* local = new NoeudListe<T>(location,location->getNext(),val);
        (*(location->getNext())).setPrev(local);
        location->setNext(local);
    }

    void insert_first(T& val)
    {
        insert_after (val, tete);
    }

    void insert_last(T& val)
    {
        insert_after (val, fin->getPrev());
    }

    friend std::ostream& operator << (std::ostream& os,const Liste<T>& location)
    {
        NoeudListe<T>* local=(location.tete)->getNext();
        while( local->getVal() != NULL )
        {
            os<< local->getVal() << "\n";
            local=local->getNext();
        }
        return os;
    }
};

-----NoeudListe.h------
#pragma once
template <class T> class NoeudListe
{

private:
    NoeudListe* prev;
    NoeudListe* next;
    T val;

public:

    NoeudListe(NoeudListe* p, NoeudListe* n, const T& v)
    {
        prev = p;
        next = n;
        val = v;
    }

    void setNext(NoeudListe* n){ next = n;}
    void setPrev(NoeudListe* p){ prev = p;}
    void setVal(const T& v){ val = v;}

    NoeudListe* getNext(){ return next;}
    NoeudListe* getPrev(){ return prev;}
    T getVal(){ return val;}

};

Answer 1

friend std::ostream& operator << (std::ostream& os,const Liste<T>& location)
{
    NoeudListe<T>* local=(location.tete)->getNext();
    while( local->getVal() != NULL )
    {
        os<< local->getVal() << "\n";
        local=local->getNext();
    }
    return os;
}

如果local为NULL（如果local->getVal()为NULL，为什么要测试？），这里不测试，所以你会在这里得到一个段错误。

写templete类听取问题

1 个答案: