static reference to vector->head,tail

#include <vector>

#include <iostream>

using namespace std;

template<class T>

class myvector:public vector<T>{

public:

T tail;

T head;

void push_back ( const T& x ){

std::vector<T>::push_back(x);

head=this->front();

tail=this->back();

}

void pop_back (){

std::vector<T>::pop_back();

head=this->front();

tail=this->back();

}

};

int main(){

class myvector<int> myv;

int & i=myv.head;

int & j=myv.tail;

myv.push_back(100);

cout<<i<<","<<j<<endl;

myv.push_back(200);

cout<<i<<","<<j<<endl;

myv.push_back(300);

cout<<i<<","<<j<<endl;

myv.pop_back(300);

cout<<i<<","<<j<<endl;

return 0;

}