Re: boost bind expression not doing what I expect

SG <>
Wed, 19 Aug 2009 02:32:53 -0700 (PDT)
On 19 Aug., 10:27, Stone Free wrote:

#include <map>
#include <set>
#include <vector>
#include <algorithm>
#include <boost/bind.hpp>

using namespace boost::bind;

typedef int DWORD;
typedef std::pair<std::string, bool> user_info;
typedef std::map<DWORD, user_info> USER_MAP;
typedef std::vector<DWORD> VEC_STAFF;

int main(int argc, _char* argv[])
   USER_MAP m_Users;
   VEC_STAFF Staff;


   VEC_STAFF::iterator it =
      std::partition( Staff.begin(), Staff.end(),
         bind(&USER_MAP::find, m_Users, _1) != m_Users.end() );

What I wanted to code to do is that for every entry in the Staff
vector it should check to see whether that user id was present in the
map, and if so move those items to the front.

[boost bind expression not doing what I expect] (subject)

At first glance, it looks okay. But you're creating a functor that
works on a *copy* of m_Users and compare an iterator of the copy with
an iterator of the original map. Try using a pointer:

  bind(&USER_MAP::find, &m_Users, _1)

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