5.不用拷贝的对象可以用ref

 #include <iostream>
 #include <string>
 #include <boost/bind.hpp>
 #include <boost/function.hpp>
 #include <vector>
 #include <algorithm>
 #include <functional>
 #include <stdlib.h>
 using namespace std;
 using namespace boost;

 void print(std::ostream &os,int i)
 {
     os << i << endl;
 }

 void mainF()
 {
     //不可以拷贝的对象可以用ref
     boost::function<void(int)> pt = boost::bind(print,boost::ref(cout), _1);

     vector<int > v;
     v.push_back();
     v.push_back();
     v.push_back();
     for_each(v.begin(), v.end(), pt);

     std::cin.get();
 }