双向链表的复制构造函数

[ankong1]

//---------------node.h--------------------------
#ifndef CHAINNODEH
#define CHAINNODEH

template<typename T> class DoubleList; //声明Double类

template<typename T>
class DoubleNode{
private:
friend DoubleList<T>; //设Double为本类的朋友

DoubleNode():left(NULL),right(NULL){}

DoubleNode(const T item,DoubleNode<T> *prior = NULL, DoubleNode<T> *next = NULL)
:data(item),left(prior),right(next){}

~DoubleNode(){
left = NULL;
right = NULL;
}

public:
T GetData();

private:

T data; //内部数据
DoubleNode<T> *left, *right; //指针左右

};

template<typename T>
T DoubleNode<T>::GetData(){ //查寻几号位的数据


return this->data;

}
#endif

//------------------DoubleList.h------------------------
#ifndef DOUBLEH
#define DOUBLEH
#include <iostream>
#include <fstream>
#include <cstdlib>
#include "node.h"
#include "except.h"
using namespace std;
template<class T>
class DoubleList{
public:
DoubleList():head( new DoubleNode<T>() ){
head->left = head;
head->right = head;
}

//拷贝构造函数不知道这么做。麻烦指点下 。

~DoubleList(){
MakeEmpty();
delete head;
}
void MakeEmpty(); //使表变空
int Length() const; //判断长度
DoubleNode<T> *Find(int n=0) const; //查找
DoubleNode<T> *FindData(T item); //find the data which is equal to item
int Search(const T& x) const; // 搜寻
bool Insert( T item,int n);
T Remove(int n=0); //delete the nth data
T Get(int n=0); // 获得第N个数据
void Print(); //print the list
private:
DoubleNode<T> *head;
}; //class Double



//--------------------------------
最好能给出代码。

[old-six-programmer]

我随便写了段代码
将你的链表无参构造函数改了一下

class DoubleList
{ 
public: 
	DoubleList():head( new DoubleNode <T>() )
	{ 
	} 
	DoubleList( const DoubleList<T>& list )
	{
		DoubleNode<T>* p = list.head;

		DoubleNode<T>* pPre = NULL;
		DoubleNode<T>* pCur = new DoubleNode<T>();
		while( 1 )
		{
			pCur->data = p->data;

			pCur->left = pPre;

			if( p->right )
				pCur->right = new DoubleNode<T>();
			else
			{
				pCur->right = NULL;
				break;
			}
	
			p = p->right;
			pPre = pCur;
			pCur = pCur->right;
		}
	}

        //我自己添加的函数，用于在链表尾部添加节点，用来测试
	void Add( T item )
	{
		if( head )
		{
			DoubleNode<T>* p = head;

			while( p->right )
				p = p->right;

			p->right = new DoubleNode<T>( item );
			p->right->left = p;
		}
		else
		{
			head = new DoubleNode<T>( item );
		}
	}
private: 
	DoubleNode <T>  *head; 
};