C++实现双向链表

C++实现双向链表

今天同学在coding的时候遇到点小麻烦，然后晚上回来的时候敲好有时间，顺便实现了一番，指针，指针，听大佬说是C语言的精髓（悄悄话）

是女装就直接上代码，少啰嗦

代码略带点注释，具体指针是怎么指向，仔细琢磨基本可以搞定，一天不行，盘他一个星期

#ifndef _DOUBLE_LIST_HPP_

#include <iostream>
using namespace std;

//结点  
typedef struct node
{
  struct node* next;
  struct node* pre;
  int data;
}Node;


class DoubleList
{
private:
  //双向链表的第一个节点（是有数据的，就是课本上的无头结点链表）
  Node* head;
  
  //表长
  int _size;


public:

  //无头结点的链表
  DoubleList(int headData)
  {
    head = new Node;
    head->pre = NULL;
    head->next = NULL;
    head->data = headData;
    
    _size = 1;
  }

  ~DoubleList()
  {
    delete head;
    head = NULL;
  }

  //从头部开始打印输出
  void print()
  {
    if (!empty())
    {
      Node* tmp = head;
      while (tmp)
      {
        cout << tmp->data << endl;
        tmp = tmp->next;
      }
    }
  }

  //从尾部开始打印输出
  void rprint()
  {
    if (!empty())
    {
      //遍历到表尾
      Node* tmp = head;
      while (tmp->next)
      {
        tmp = tmp->next;
      }

      //反向遍历
      while (tmp)
      {
        cout << tmp->data << endl;
        tmp = tmp->pre;
      }
    }
  }

  //尾插法
  bool insertEnd(int data)
  {
    Node* tmp = head;
    while (tmp->next)
    {
      tmp = tmp->next;
    }

    //insert
    Node* _node = new Node;
    _node->data = data;
    _node->next = NULL;
    tmp->next = _node;
    _node->pre = tmp;

    ++_size;
    return false;
  }

  //头插法
  bool insertBegin(int data)
  {
    Node* tmp = head;
    //insert
    Node* _node = new Node;
    _node->data = data;
    _node->pre = NULL;
    _node->next = tmp;
    head = _node; 
    
    ++_size;
    return false;
  }

  //删除某个元素
  bool Delete(int data)
  {
    Node* tmp = findElement(data);
    if (!tmp)
    {
      cout << data << "不存在" << endl;
      return false;
    }

    if (tmp->next == NULL)
    { 
      deleteEnd();
    }
    else if (tmp->pre == NULL)
    {
      deleteBegin();    
    }
    else
    {
      Node* tmpNext = tmp->next;
      tmp->pre->next = tmpNext;
      tmpNext->pre = tmp->pre;
          
    }

    --_size;
    close(tmp);
    return true;
  }

  //删除头元素
  bool deleteBegin()
  {
    Node* tmp = head;
    Node* t = tmp->next;
    t->pre = NULL;
    head = t;

    --_size;
    close(tmp);   
    return false;
  }

  //删除尾元素
  bool deleteEnd()
  {
    Node* tmp = head;
    while (tmp->next)
    {
      tmp = tmp->next;
    }

    Node* t = tmp;
    t->pre->next = NULL;
    
    --_size;
    close(tmp);
    return false;
  }

  //查找某元素是否在里面
  bool find(int data)
  {
    Node tmp = *head;

    while (tmp.next)
    {
      if (tmp.data == data)
      {
        return true;
      }
      tmp = *tmp.next;
    }

    return false;
  }

  //直接获取表长
  int size()
  {
    return _size;
  }

  //清空链表
  void clear()
  {
    Node* tmp = head->next;
    
    while (tmp)
    {
      --_size;
      close(head);
      head = tmp;
      tmp = tmp->next;
    }

    --_size;
    head->next = NULL;
    head->pre  = NULL;
    head->data = 0;
    //close(head);
    //close(head);
  }

  //判断是否为空
  bool empty()
  {
    return _size >= 0 ? false: true;
  }
  
  //取头元素
  int font()
  {
    return head->data;
  }

  //取尾元素
  int back()
  {
    Node tmp = *head;
    while (tmp.next)
    {
      tmp = *tmp.next;
    }

    return tmp.data;
  }

private:

  //查找元素结点
  Node* findElement(int data)
  {
    Node* tmp = head;

    while (tmp)
    {
      if (tmp->data == data)
      {
        return tmp;
      }
      tmp = tmp->next;
    }

    return NULL;
  }

  //释放某结点内存
  void close(Node* node)
  {
    delete node;
    node = NULL;
  }

};


int main()
{
  cout << "双向链表" << endl;
  DoubleList* dlist = new DoubleList(1);
  for (int i = 2; i <= 5; i++)
  {
    //表头插入
    dlist->insertEnd(i);
  }


///
  //测试


  cout << "-------------------" << endl;
  dlist->print();

  /*if (dlist->find(4))
  {
    cout << "yes" << endl;
  }
  else {
    cout << "no" << endl;
  }*/

  cout<<dlist->font()<<endl;
  cout << dlist->back() << endl;


  //打印输出
  /*cout << "-------------------" << endl;
  dlist->print();
  cout << "-------------------" << endl;
  dlist->rprint();
  cout << "size=" << dlist->size()<<"   "<<dlist->length() << endl;
*/
  //表尾
  //dlist->insertEnd(5);

  //删除中间、开头、结尾都可以
  //dlist->Delete(3);

  //删除开头
  /*dlist->deleteBegin();
  dlist->deleteBegin();
  dlist->deleteBegin();*/

  //删除结尾
  /*dlist->deleteEnd();
  dlist->deleteEnd();
  dlist->deleteEnd();
  */

  /*cout << "-------------------" << endl;
  dlist->print();
  cout << "size=" << dlist->size() << "   "  << endl;
  dlist->clear();
  cout << "size=" << dlist->size() << "   "  << endl;
  cout << "-------------------" << endl;
  dlist->print();*/


  cin.get();
  return 0;
}


#endif // !_DOUBLE_LIST_HPP_