Class linked list

Question

I'm a newbie and I don't understant clearly about linked list, so when I write my program, I'm in trouble with it . It have a error in ostream& operator<<(ostream& os, const LinkedList &ll) and I don't figure out. This is my code:

LinkedList.h

#pragma once
#include<iostream>
using namespace std;
struct Node
{
    int infor;
    Node *pNext;
};
class LinkedList
{
    Node *pHead, *pTail;
    int curN;
public:
    //default constructor
    LinkedList();
    //destructor
    ~LinkedList();
    static Node* CreateNode(const int& n);
    Node* AddHead(const int &n);
    Node* AddTail(const int &n);
    Node* RemoveHead();  
    Node* RemoveTail();  
    friend ostream& operator<<(ostream& os, const LinkedList &ll);
    int& operator[](const int& i);
    static int SoNguyenMax();
};

LinkedList.cpp

#include "LinkList.h"

LinkedList::LinkedList()
{
    pHead = pTail = NULL;
}
LinkedList::~LinkedList()
{
}
static Node* CreateNode(const int &n)
{
    Node *NewNode = new Node;
    if (NewNode == NULL)
    {
        cout << "Khong du bo nho" << endl;
        return NULL;
    }
    else 
    {
        NewNode->infor = n;
        NewNode->pNext = NULL;
    }
    return NewNode;
}
Node* LinkedList::AddHead(const int &n)
{
    Node *u = new Node;
    u->infor = n;
    if (pHead == NULL)
        pHead = pTail = u;
    else
    {
        u->pNext = pHead;
        pHead = u;
    }
    return pHead;
}
Node* LinkedList::AddTail(const int &n)
{
    Node *u = new Node;
    u->infor = n;
    if (pHead == NULL)
        pHead = pTail = u;
    else
    {
        pTail->pNext = u;
        pTail = u;
    }
    return pTail;
}
Node* LinkedList::RemoveHead()
{
    Node *p;
    p = pHead;
    pHead = pHead->pNext;
    delete p;
    return pHead;
}
Node* LinkedList::RemoveTail()
{
    Node *p, *q;
    p = pHead;
    while (p != pTail)
    {
        q = p;
        p = p->pNext;
    }
    pTail = q;
    q->pNext = NULL;
    delete p;
    return pTail;
}
ostream& operator<<(ostream& os, const LinkedList &ll)
{
    for (Node *k = ll.pHead; k != NULL; k = k->pNext)
        os << k->infor << "   ";
    return os;
}

main function

#include"LinkList.h"
int main()
{
    LinkedList l;
    l.AddHead(15);
    l.AddHead(123456);
    cout << l << endl;
    return 0;
}

and: [Autos table: ]

k 0xcdcdcdcd {infor=??? pNext=??? } Node *
ll.pHead 0x00abf4d8 {infor=123456 pNext=0x00abf238 {infor=15 pNext=0xcdcdcdcd {infor=??? pNext=??? } } } Node * const
ll{pHead=0x00abf4d8 {infor=123456 pNext=0x00abf238 {infor=15 pNext=0xcdcdcdcd {infor=??? pNext=??? } } } ...}

Please help me. Thanks!

If this is visual studio copy the text of the error message from the Output tab. — drescherjm, Oct 24 '16 at 03:31
0xcdcdcdcd = uninitialized heap memory: http://stackoverflow.com/questions/127386/in-visual-studio-c-what-are-the-memory-allocation-representations/127404#127404 — drescherjm, Oct 24 '16 at 14:09
You are not initializing the pNext pointers when adding a head or a tail to an empty list. Also RemoveHead blindly removes the head even if the list is empty. And new should throw an exception (std::bad_alloc) instead of returning NULL on an out of memory with a modern c++ compiler. — drescherjm, Oct 24 '16 at 14:15
but when I remove "static" in static Node* CreateNode(const int& n); it has no error. I don't understand why — I_love_mom, Oct 24 '16 at 16:47
Undefined Behavior can sometimes make bad / improper code appear to work. — drescherjm, Oct 24 '16 at 17:10

score 0 · Answer 1 · edited Oct 29 '16 at 10:12

0

Try using a while loop:

ostream& operator << (ostream &os, const LinkedList &ll)
{
    Node* k = ll.pHead;
    while (k != NULL)
    {
        os << k->_data << ", ";
        k = k->pNext;
    }
    return os;
}

But I found something. "INFOR" variable can be confused with "INFO".

edited Oct 29 '16 at 10:12

Tim Potter

2,437
21
31

answered Oct 29 '16 at 09:49

Duy Truong

11
2

Class linked list

1 Answers1