C++实现vector

  1 //my Vecter ;T need "operator<"
  2 
  3 #include <iostream>
  4 using std::cout;
  5 using std::ostream;
  6 
  7 template <typename T>
  8 struct item
  9 {
 10     item():value(),next(NULL),last(NULL){}
 11     item(const T t):value(t),next(NULL),last(NULL){}
 12     item *next,*last;
 13     T value;
 14 };
 15 
 16 template <typename T>
 17 class Vector
 18 {
 19     public:
 20     Vector():m_size(0),m_head(NULL){}
 21     int size() const{return m_size;}
 22     bool empty() const{return m_size?true:false;}
 23     T front() const{return m_size?m_head->value:T();}
 24     T back() const{return m_size?end()->value:T();}
 25     bool push_back(const T&);
 26     bool push_front(const T&);
 27     T pop_back();
 28     T pop_front();
 29     void erase(int pos,int num);
 30     void clear();
 31     T& operator[](const int key);
 32     void sort();
 33     Vector<T>& operator=(Vector<T>& v);
 34 
 35     private:
 36     item<T> * end() const;
 37     int m_size;
 38     item<T> *m_head;
 39     int partition(int,int);
 40     void qsort(int,int);
 41 };
 42 
 43 template <typename T>
 44 bool Vector<T>::push_back(const T& t)
 45 {
 46     if(m_size==0)
 47     {
 48         m_head=new item<T>;
 49         m_head->value=t;
 50     }
 51     else
 52     {
 53         item<T>* save=end();
 54         save->next=new item<T>(t);
 55         save->next->last=save;
 56     }
 57     m_size++;
 58     return true;
 59 }
 60 
 61 template <typename T>
 62 bool Vector<T>::push_front(const T& t)
 63 {
 64     if(m_size==0)
 65     {
 66         m_head=new item<T>(t);
 67         return true;
 68     }
 69     item<T> *save=m_head;
 70     m_head=new item<T>(t);
 71     m_head->next=save;
 72     m_size++;
 73     if(save!=NULL)save->last=m_head;
 74     return true;
 75 }
 76 
 77 template <typename T>
 78 T Vector<T>::pop_front()
 79 {
 80     if(m_size==0)return T();
 81     if(m_size==1)
 82     {
 83         T t=m_head->value;
 84         delete m_head;
 85         m_head=NULL;
 86         m_size--;
 87         return t;
 88     }
 89     item<T>* save=m_head->next;
 90     T t=m_head->value;
 91     delete m_head;
 92     m_head=save;
 93     save->last=m_head;
 94     m_size--;
 95     return t;
 96 }
 97 
 98 template <typename T>
 99 T Vector<T>::pop_back()
100 {
101     if(m_size==0)return T();
102     if(m_size==1)
103     {
104         T t=m_head->value;
105         delete m_head;
106         m_head=NULL;
107         m_size--;
108         return t;
109     }
110     item<T>* e=end();
111     T t=e->value;
112     e->last->next=NULL;
113     delete e;
114     m_size--;
115     return t;
116 }
117 
118 template <typename T>
119 void Vector<T>::erase(int pos,int num)
120 {
121     if(m_size<pos+1)return;
122     else
123     {
124         item<T> *p=m_head,*save;
125         for(int i=0;i<pos;i++){p=p->next;}
126         for(int i=0;i<num;i++)
127         {
128             if(p==NULL)break;
129             save=p;
130             if(p->last==NULL){m_head=p->next;}
131             else p->last->next=p->next;
132             if(p->next!=NULL)p->next->last=p->last;
133             p=p->next;
134             delete save;
135             m_size--;
136         }
137     }
138 }
139 
140 template <typename T>
141 T& Vector<T>::operator[](const int key)
142 {
143     if(key+1>m_size)m_size=(key+1);
144     item<T> *p=m_head,*save;
145     for(int i=0;i<key+1;i++)
146     {
147         if(m_head==NULL)
148         {
149             m_head=new item<T>;
150             save=p=m_head;
151         }
152         else if(p==NULL)
153         {
154             p=new item<T>;
155             p->last=save;
156             save->next=p;
157         }
158         save=p;
159         p=p->next;
160     }
161     return save->value;
162 }
163 
164 template <typename T>
165 void Vector<T>::clear()
166 {
167     erase(0,m_size);
168 }
169 
170 template <typename T>
171 item<T>* Vector<T>::end() const
172 {
173     if(m_size==0)return NULL;
174     item<T> *p=m_head;
175     for(; p->next!=NULL; p=p->next);
176     return p;
177 }
178 
179 template <typename T>
180 int Vector<T>::partition(int p,int r)
181 {
182     int x=(*this)[r];
183     int i=p-1,temp;
184     for(int j=p;j<=r-1;j++)
185     {
186         if((*this)[j]<x)
187         {
188             i++;
189             if(i!=j)
190             {temp=(*this)[i];(*this)[i]=(*this)[j];(*this)[j]=temp;}
191         }
192     }
193     if(r!=i+1)
194     {temp=(*this)[r];(*this)[r]=(*this)[i+1];(*this)[i+1]=temp;}
195     return i+1;
196 }
197 
198 template <typename T>
199 void Vector<T>::sort()
200 {
201     qsort(0,m_size-1);
202 }
203 template <typename T>
204 void Vector<T>::qsort(int p,int r)
205 {
206     if(p<r)
207     {
208         int q=partition(p,r);
209         qsort(p,q-1);
210         qsort(q+1,r);
211     }
212 }
213 
214 template<typename T>
215 ostream& operator<<(ostream& out,Vector<T> &v)
216 {
217     for(int i=0;i<v.size();i++)
218     {
219         out<<v[i]<<" ";
220     }
221     return out;
222 }
223 template<typename T>
224 Vector<T>& Vector<T>::operator=(Vector& v)
225 {
226     this->clear();
227     m_size=v.m_size;
228     item<T> *p=m_head,*vp=v.m_head;
229     for(int i=0;i<m_size;i++)
230     {
231         p=new item<T>(vp->value);
232         p=p->next;
233         vp=vp->next;
234     }
235     return *this;
236 }
237 
238 int main()
239 {
240     int i=10;
241     Vector<int> v;
242     v.push_back(i);i--;
243     v.push_front(i);
244     v.push_back(i);i--;
245     v.push_front(i);
246     v[8]=5414;
247     cout<<v<<"\n";
248     v.erase(2,3);
249     cout<<v<<"\n";
250     v.clear();
251     for(int i=10;i>0;i--)v[i]=5-i;
252     v[5]=12;
253     v[15]=77;
254     cout<<v<<"\n";
255     v.sort();
256     cout<<"V1= "<<v<<"\n";
257     Vector<int> v2=v;
258     cout<<"V2= "<<v2<<"\n";
259     return 0;
260 }