单向链表LinkedList的使用

单向链表LinkedList的使用

为了理解链表的作用，以及对于node class的reuse，将Node和LinkedList分开写成class文件。
LinkedList 用来完成链表的结构框架，其中包括

• void addToStart(Node*);
• void addToEnd(Node*);
• void printList();
• bool removeFromStart();
• bool removeFromEnd();
• void removeNodeFromList(int);
• void removeNodeFromList(string);
• 在链表头部增加节点
• 在链表尾部增加节点
• 显示链表的内容
• 移除链表头部节点
• 移除链表尾部节点

• 移除指定内容的节点

  cpp文件包括

• Node.h
• LinkedList.h
• LinkedList.cpp
  < 第一次写的过程中遇到pointer being freed was not allocated 的错误，原因是将 temp = head, delete head后delete temp。head 与temp 同指向一块内存区域，当将head的内存区域释放后，temp成为空指针。>
  Node.h

using namespace std;class Node{//申明LinkedList为友元类，在Node class中可以直接调用LinkedList中成员    friend class LinkedList; //无参构造函数，有参构造函数    Node(){        this->next = NULL;    };    //可以根据需求改变node节点中变量，如多个int 变量    Node(string name, int no){        this->itemName = name;        this->itemNo = no;        this->next = NULL;    } private:    string itemName;    int itemNo;    Node* next;}；

LinkedList.h

ifndef __ShopList__LinkedList__ #define __ShopList__LinkedList__ #include "Node.h"class LinkedList:public Node{public:    LinkedList();    ~LinkedList();    int size() const;    void addToStart(Node*);    void addToEnd(Node*);    void printList();    bool removeFromStart();    bool removeFromEnd();    void removeNodeFromList(int);    void removeNodeFromList(string);private:    Node* head; //指向链表头    Node* curr; //指向链表当前的node，相当于变量i历遍数组    Node* temp; //临时变量链表指针    int mySize; //记录链表中node数量};endif /* defined(__ShopList__LinkedList__) */ #include "LinkedList.h"

//
// LinkedList.cpp
// ShopList

#include "LinkedList.h"LinkedList::LinkedList(){    head = NULL;    curr = NULL;    temp = NULL;    mySize = 0;    //全部初始化为0}LinkedList::~LinkedList(){}int LinkedList::size() const{    return mySize; //返回链表的结点个数}void LinkedList::addToStart(Node *n){//如果链表头是空值，直接将当前Node 指针指向链表头head//如果链表头是非空值，将原来链表头右移一位，即n->next = head,再将当前 Node n指向head    if (head != NULL){        n->next = head;        head = n;    }else{        head = n;    }    printList();    mySize++;}void LinkedList::addToEnd(Node *n){//    如果 head != null, go to the end of the list, use the next of last node pointing to new node//    如果 head == null, head = new node    if (head != NULL) {        curr = head;        while(curr->next != NULL){            curr = curr->next;        }        curr->next = n;    }else{        head = n;    }    printList();    mySize++;}void LinkedList::printList(){    curr = head;    if(head == NULL)        cout<<"Shopping List is empty"<<endl;    cout<<"Item NO\tItem Name"<<endl;    while(curr != NULL){        cout<<curr->itemNo<<"\t"<<curr->itemName<<endl;        curr = curr->next;    }}bool LinkedList::removeFromStart(){    if(head == NULL)        return false;    if(head->next == NULL){        head = head->next;    }else{        temp = head->next;        delete head;        head = temp;    }    mySize--;    printList();    return true;}bool LinkedList::removeFromEnd(){    if(head == NULL)            //when head is not null        return false;                   //go to the last node in the list    curr = head;    temp = head;    while (curr->next != NULL){      //para@ temp current node before coming to the next one        temp = curr;        curr = curr->next;    }    if(curr == head)        head = head->next;    else{        temp->next = NULL;        delete curr;    }    mySize--;    printList();    return true;}void LinkedList::removeNodeFromList(int n){    temp = head;    curr = head;    if (head == NULL) return;    if (head->itemNo == n) {        head = curr->next;        delete temp;        temp = head;        mySize--;        printList();        return;    }//    go through the list to find delete data    while(curr != NULL && curr->itemNo != n){//    para@ temp current node before coming to the next one        temp = curr;        curr = curr->next;    }/ when curr = null it means delete element is not in the list    if (curr == NULL){        cout<<"Item not found"<<endl;    }else{        temp->next = curr->next;        delete curr;        mySize--;        printList();    }}void LinkedList::removeNodeFromList(string s){    temp = head;    curr = head;    if (head == NULL) return;    if (head->itemName == s) {        head = curr->next;        delete temp;        temp = head;        printList();        mySize--;        return;    }    //    go through the list to find delete data    while(curr != NULL && curr->itemName != s){        // para@ temp current node before coming to the next one        temp = curr;        curr = curr->next;    }//when curr = null it means delete element is not in the list    if (curr == NULL){        cout<<"Item not found"<<endl;    }else{        temp->next = curr->next;        delete curr;        mySize--;        printList();    }}