#include "AccessList.h"
using namespace std;

void AccessList::addUser(const string& user)
{
  mAllowed.insert(user);
}

void AccessList::removeUser(const string& user)
{
  mAllowed.erase(user);
}

bool AccessList::isAllowed(const string& user) const
{
  return (mAllowed.count(user) == 1);
}

list<string> AccessList::getAllUsers() const
{
  list<string> users;
  users.insert(users.end(), mAllowed.begin(), mAllowed.end());
  return (users);
}

I just test a sample in the 21st chapter, but some error in it?
//compiled results:574841_ch21\accesscontrollist\accesslist.c pp(22) : error C2664: 'void __thiscall std::list<class std::basic_string<char,struct std::char_traits<char>,class std::allocator......

ok! No error in g++.