c/c++语言开发共享c++双向链表构成的队列

c++双向链表构成的队列：也可以看成循环队列的。需要仔细，重点是插入与弹出，结合前篇的绘图，总结逻辑是：1先外部元素建立连接，2后内部元素改变连接。

3改变内部元素连接时，留意前驱或后驱是否为空时的特例。
以下是自定义实现：

//circularqueue.h

  #ifdef _msc_ver  #pragma once  #endif // _msc_ver    #ifndef circular_queue_h_h_  #define circular_queue_h_h_    #include  #include    /** 此容器保存的数据类型 */  typedef int datatype;    /** 结点类型 */  struct node  {      datatype data_;      node* next_;      node* prev_;  };    class circularqueue  {      node* pfront;       ///< 指向头结点      node* pback;        ///< 指向尾结点      int maxsize_;       ///< 最大可用容量      int size_;          ///< 已使用的容量  public:      /** 构造函数，传入最大容量参数 */      explicit circularqueue(int maxsize);      ~circularqueue();        /** 从尾部插入 */      int push_back(datatype data);        /** 从头部弹出 */      int pop_front();        /** 返回头结点的数据 */      datatype front();        /** 已使用的容量 */      int size();        /** 空队判断 */      bool empty();        /** 满队判断 */      bool full();  };    #endif // !circular_queue_h_h_  

//circularqueue.cpp

  #include "circularqueue.h"    circularqueue::circularqueue(int maxsize)  {      assert(maxsize > 0);      pfront=null;      pback=null;      maxsize_ = maxsize;      size_ = 0;  }    circularqueue::~circularqueue()  {      node* tempnode;      while (pfront !=null)      {          tempnode = pfront->next_;          delete pfront;          pfront = tempnode;      }  }    int circularqueue::push_back(datatype data)  {      assert(!full());        node* newnode = new node;      newnode->data_ = data;      if (empty())      {          // 构造队列          newnode->next_ = null;          newnode->prev_ = null;          pback=pfront = newnode;        }      else      {          // 队尾插入          newnode->prev_ = pback;          newnode->next_ = pback->next_;          pback->next_ = newnode;          pback = newnode;      }      size_++;        return 0;  }    int circularqueue::pop_front()  {      assert(!empty());      node* tempnode = pfront;        if (pfront->next_!=null)      {          pfront->next_->prev_ = pfront->prev_;      }      pfront = pfront->next_;      delete tempnode;      size_--;        return 0;  }    datatype circularqueue::front()  {      assert(!empty());      return pfront->data_;  }    int circularqueue::size()  {      return size_;  }    bool circularqueue::empty()  {      return size_==0;  }    bool circularqueue::full()  {      return size_ == maxsize_;  }  

//test.cpp

  #include  #include"vector.h"    using std::cout;  using std::endl;      int main()  {      std::cout << "hello" << std::endl;      circularqueue queue(3);      queue.push_back(1);      queue.push_back(2);      queue.push_back(3);      cout << queue.front() << "-" << queue.size() << endl;      queue.pop_front();      cout << queue.front() << "-" << queue.size() << endl;      queue.pop_front();      cout << queue.front() << "-" << queue.size() << endl;        queue.pop_front();      queue.push_back(4);      queue.push_back(5);      queue.push_back(6);      cout << queue.front() << "-" << queue.size() << endl;        queue.pop_front();      cout << queue.front() << "-" << queue.size() << endl;      queue.pop_front();      cout << queue.front() << "-" << queue.size() << endl;      queue.pop_front();      cout << "-" << queue.size() << endl;        return 0;  }