一个单向链表，并实现栈和队列

以下是本人学习中写的一个简单的链表和棧以及队列的实现，由于时间问题没有注释，但命名都很直观.很多不足之处正在慢慢探索学习中。
代码贴上来显示就有问题，不知道是CSDN的问题还是格式的问题，在我自己机子上没问题的，郁闷！

#include using namespace std;#include typedef double T;/*单向链表类*/class List{struct Node{T data;Node* next;Node(const T& t=T()):data(t),next(NULL){}};Node* head;public :List():head(NULL){}void clear(){while(head!=NULL){Node* q=head->next;delete head;head=q;}}~List(){clear();}void insert_front(const T& t){Node* p=new Node(t);p->next=head;head=p;}void insert_back(const T& t){Node* p=new Node(t);Node* q=head;if(head==NULL)head=p;else{while(q->next!=NULL)q=q->next;q->next=p;}}void travel(){Node* p=head;while(p!=NULL){cout<data<<&apos; &apos;;p=p->next;}cout<next;}return cnt;}T getHead(){if(head==NULL)throw "no head !";return head->data;}T getTail(){if(head==NULL) throw "no tail !";Node* p=head;while(p->next!=NULL){p=p->next;}return p->data;}bool empty(){return head==NULL;}int find(const T& t){Node* p=head;int pos=0;while(p!=NULL){if(p->data==t)return pos;p=p->next;pos++;}return -1;}bool update(const T& o,const T& n){int pos=find(0);if(pos==-1)return false;Node* p=getPointer(pos);p->data=n;return true;}private :Node* getPointer(int pos){Node* p=head;for(int i=0;inext;}return p;}public :bool erase(const T& t){int pos=find(t);if(pos==-1)return false;if(pos==0){Node* q=head->next;delete head;head=q;}else{Node* pre=getPointer(pos-1);Node* cur=pre->next;pre->next=cur->next;delete cur;}return true;}};/*栈类  */class Stack{List l;public :void push(const T& t){l.insert_front(t);}void pop(){l.erase(l.getHead());}T top(){return l.getHead();}bool empty(){return l.empty();}int size(){return l.size();}void clear(){l.clear();}};/*队列类*/class Queue{List l;public :void push(const T& t){l.insert_back(t);}void pop(){l.erase(l.getHead());}T front(){return l.getHead();}T back(){return l.getTail();}bool empty(){return l.empty();}int size(){return l.size();}void clear(){l.clear();}};void main(){//自己的测试代码}