学生成绩——双链表

#include<iostream>  
using namespace std;  
template <class student>  
class  Node  
{  
public:  
    student data;  
    Node<student> *prior;  
    Node<student> *next;  
};  
template <class student>  
class DLL 
{  
public:  
    DLL();  //无参的构造函数
    DLL(student score[], int n);  //带参的构造函数  
    ~DLL();  //析构函数  
    int Length(); //返回单链表长度  
    void insert(int i, student x); //插入操作，在位置i插入元素  
    student get(int i);  //按位查找  
    int locate(student x);  //按值查找  
    student Delete(int i);  //删除操作  
    void print();  //遍历操作  
private:  
    Node<student> *first;  //双链表的头指针  
    int length;   //链的长度计数  
};  
template <class student>  
DLL<student>::DLL(student score[], int n)  
{  
    length=0;  
    first=new Node<student>;  
    first->next=NULL;  
    first->prior=NULL;  
    for (int i=0;i<n;i++)  
    {  
        Node<student> *s=new Node<student>;  
        s->data=score[i];  
        s->next=first->next;   
        first->next = s;  
    }  
}  
template <class student>  
DLL<student>::~DLL()  
{  
    while (first->next!=first->prior)  
    {  
        //临时指针，存储即将释放的节点的指针  
        Node<student> *temp=first;  
        //脱链  
        first->prior->next=first->next;  
        first->next ->prior=first->prior;  
        //头指针后移  
        first=first->next;  
        //释放内存  
        delete temp;  
    }  
    delete first;  
}  
  
template<class student>  
int DLL<student>::Length()  
{  
    Node<student> *p; 
	int count;  
    p=first->next;    
    count=0;    
    while(p!=NULL)  
    {    
        p=p->next;    
        count++;    
     }    
    return length;  
}  
  
template <class student>  
void DLL<student>::insert(int i,student x)  
{  
    Node<student>*p,*s;
	int count;    
    p=first;     
    count=0;    
    while(p!=NULL&&count<i-1)    
    {    
        p=p->next;    
        count++;            
     }    
     if(p==NULL) throw"位置";    
     else  
     {    
       s=new Node<student>;    
       s->data=x;    
       s->next=p->next;    
       p->next=s;    
     }  
}  
  
template <class student>  
student DLL<student>::get(int i)  
{  
    Node<student> *p;int count; 
	count=1;  
    p=first->next;   
    while (p!=NULL&&count<i)  
    {  
        p = p->next;
		count++;  
    }  
    if (p == NULL)throw"位置非法";  
    else return p->data;  
}  
  
template <class student>  
int DLL<student>::locate(student x)  
{  
    Node<student> *p;
	int count;  
    p=first->next; 
	count=1;  
    while(p!=NULL)  
    {  
        if(p->data==x) return count;  
        p=p->next;  
        count++;  
    }  
    return 0;  
}  
  
template <class student>  
student DLL<student>::Delete(int i)  
{  
    Node<student> *p,*q;  
    p=first->next; 
	int count, x;
	count=1;  
    while (p!=NULL&&count<i-1)  
    {  
        p=p->next; 
		count++;  
    }  
    if (p==NULL||p->next==NULL) throw"位置非法";  
    else  
    {    
        q=p->next;    
        x=q->data;    
        if (p->next!=NULL)  
        {    
            if(q->next!=NULL)    
        q->next->prior=p;  
            else  
            {  
                p->next=NULL;  
                p->next=q->next;  
                delete q;  
                q=NULL;  
                return x;  
            }  
        }  
        p->next=q->next;  
        delete q;    
        q=NULL;    
        return x;  
    }  
}  
  
template <class student>  
void DLL<student>::print()  
{  
    Node<student> *p;  
    p=first->next;  
    while(p->next!=NULL)  
    {  
        cout<<p->data<<" ";  
        p=p->next;  
    }  
    cout<<p->data<<endl;  
}  
int main()  
{  
    float score[8] = {72,88,57,83.5,32.5,68,96,86.5};  
    DLL<float>Student(score, 8);  
    cout<<"初始成绩如下："<<endl;  
    Student.print();  
    cout<<endl<<"在学生3插入成绩86，插入后结果如下："<<endl;  
    Student.insert(3,86);  
    Student.print();  
    cout<<endl<<"在学生5删除成绩为："<<Student.Delete(5)<<" , "<<"删除后结果如下:"<<endl;  
    Student.print();  
    cout<<endl<<"位置6的成绩为："<<Student.get(6)<<endl;  
    cout<<endl<<"成绩72所在位置为："<<Student.locate(72)<<endl<<endl;  
	cout<<"最终数据如下："<<endl;
	Student.print();
	cout<<endl;
	return 0;
}