C++实现vector

用了双向链表，快排，<<,=,[]重载，还有erase的实现比较好玩

 //my Vecter ;T need "operator<"
 
 #include <iostream>
 using std::cout;
 using std::ostream;
 
 template <typename T>
 struct item
 {
     item():value(),next(NULL),last(NULL){}
     item(const T t):value(t),next(NULL),last(NULL){}
     item *next,*last;
     T value;
 };
 
 template <typename T>
 class Vector
 {
     public:
     Vector():m_size(),m_head(NULL){}
     int size() const{return m_size;}
     bool empty() const{return m_size?true:false;}
     T front() const{return m_size?m_head->value:T();}
     T back() const{return m_size?end()->value:T();}
     bool push_back(const T&);
     bool push_front(const T&);
     T pop_back();
     T pop_front();
     void erase(int pos,int num);
     void clear();
     T& operator[](const int key);
     void sort();
     Vector<T>& operator=(Vector<T>& v);
 
     private:
     item<T> * end() const;
     int m_size;
     item<T> *m_head;
     int partition(int,int);
     void qsort(int,int);
 };
 
 template <typename T>
 bool Vector<T>::push_back(const T& t)
 {
     if(m_size==)
     {
         m_head=new item<T>;
         m_head->value=t;
     }
     else
     {
         item<T>* save=end();
         save->next=new item<T>(t);
         save->next->last=save;
     }
     m_size++;
     return true;
 }
 
 template <typename T>
 bool Vector<T>::push_front(const T& t)
 {
     if(m_size==)
     {
         m_head=new item<T>(t);
         return true;
     }
     item<T> *save=m_head;
     m_head=new item<T>(t);
     m_head->next=save;
     m_size++;
     if(save!=NULL)save->last=m_head;
     return true;
 }
 
 template <typename T>
 T Vector<T>::pop_front()
 {
     if(m_size==)return T();
     if(m_size==)
     {
         T t=m_head->value;
         delete m_head;
         m_head=NULL;
         m_size--;
         return t;
     }
     item<T>* save=m_head->next;
     T t=m_head->value;
     delete m_head;
     m_head=save;
     save->last=m_head;
     m_size--;
     return t;
 }
 
 template <typename T>
 T Vector<T>::pop_back()
 {
     if(m_size==)return T();
     if(m_size==)
     {
         T t=m_head->value;
         delete m_head;
         m_head=NULL;
         m_size--;
         return t;
     }
     item<T>* e=end();
     T t=e->value;
     e->last->next=NULL;
     delete e;
     m_size--;
     return t;
 }
 
 template <typename T>
 void Vector<T>::erase(int pos,int num)
 {
     if(m_size<pos+)return;
     else
     {
         item<T> *p=m_head,*save;
         for(int i=;i<pos;i++){p=p->next;}
         for(int i=;i<num;i++)
         {
             if(p==NULL)break;
             save=p;
             if(p->last==NULL){m_head=p->next;}
             else p->last->next=p->next;
             if(p->next!=NULL)p->next->last=p->last;
             p=p->next;
             delete save;
             m_size--;
         }
     }
 }
 
 template <typename T>
 T& Vector<T>::operator[](const int key)
 {
     if(key+>m_size)m_size=(key+);
     item<T> *p=m_head,*save;
     for(int i=;i<key+;i++)
     {
         if(m_head==NULL)
         {
             m_head=new item<T>;
             save=p=m_head;
         }
         else if(p==NULL)
         {
             p=new item<T>;
             p->last=save;
             save->next=p;
         }
         save=p;
         p=p->next;
     }
     return save->value;
 }
 
 template <typename T>
 void Vector<T>::clear()
 {
     erase(,m_size);
 }
 
 template <typename T>
 item<T>* Vector<T>::end() const
 {
     if(m_size==)return NULL;
     item<T> *p=m_head;
     for(; p->next!=NULL; p=p->next);
     return p;
 }
 
 template <typename T>
 int Vector<T>::partition(int p,int r)
 {
     T x=(*this)[r];
     int i=p-;T temp;
     for(int j=p;j<=r-;j++)
     {
         if((*this)[j]<x)
         {
             i++;
             if(i!=j)
             {temp=(*this)[i];(*this)[i]=(*this)[j];(*this)[j]=temp;}
         }
     }
     if(r!=i+)
     {temp=(*this)[r];(*this)[r]=(*this)[i+];(*this)[i+]=temp;}
     return i+;
 }
 
 template <typename T>
 void Vector<T>::sort()
 {
     qsort(,m_size-);
 }
 template <typename T>
 void Vector<T>::qsort(int p,int r)
 {
     if(p<r)
     {
         int q=partition(p,r);
         qsort(p,q-);
         qsort(q+,r);
     }
 }
 
 template<typename T>
 ostream& operator<<(ostream& out,Vector<T> &v)
 {
     for(int i=;i<v.size();i++)
     {
         out<<v[i]<<" ";
     }
     return out;
 }
 template<typename T>
 Vector<T>& Vector<T>::operator=(Vector& v)
 {
     this->clear();
     m_size=v.m_size;
     item<T> *p=m_head,*vp=v.m_head;
     for(int i=;i<m_size;i++)
     {
         p=new item<T>(vp->value);
         p=p->next;
         vp=vp->next;
     }
     return *this;
 }
 
 int main()
 {
     int i=;
     Vector<int> v;
     v.push_back(i);i--;
     v.push_front(i);
     v.push_back(i);i--;
     v.push_front(i);
     v[]=;
     cout<<v<<"\n";
     v.erase(,);
     cout<<v<<"\n";
     v.clear();
     for(int i=;i>;i--)v[i]=-i;
     v[]=;
     v[]=;
     cout<<v<<"\n";
     v.sort();
     cout<<"V1= "<<v<<"\n";
     Vector<int> v2=v;
     cout<<"V2= "<<v2<<"\n";
     return ;
 }