实现一个可以用于bind2nd的函数对象

template<typename T>class Mulitiplies:public binary_function<T,T,T>{public:Mulitiplies(){}~Mulitiplies(){}T operator()(T x,T y) const{    return x*y*3.14159265;}};int main(){    vector<double> vecs_int;    for(double i=0;i<20;i++)    {        vecs_int.push_back(i);    }    list<double> lits_int;    try    {        vecs_int.at(23);    }    catch(out_of_range &ot)    {        cout<<ot.what()<<endl;    }    //copy(vecs_int.begin(),vecs_int.end(),back_inserter(lits_int));    transform(vecs_int.begin(),vecs_int.end(),back_inserter(lits_int),bind2nd(Mulitiplies<double>(),4));    copy(lits_int.begin(),lits_int.end(),ostream_iterator<double>(cout," "));return 0;}