Re: To retrieve Keys or values of a Map

From:
Saeed Amrollahi <amrollahi.saeed@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Fri, 6 Nov 2009 08:23:06 -0800 (PST)
Message-ID:
<1d416afd-bd21-4293-a1e2-ec3baf0c6d17@s31g2000yqs.googlegroups.com>
On Nov 5, 5:30 pm, mzdude <jsa...@cox.net> wrote:

On Nov 4, 4:44 am, Saeed Amrollahi <amrollahi.sa...@gmail.com> wrote:

Dear all

I have a question. Is there any generic algorithm or solution to
access the keys or values
of a map? I frequently face to such problem and I usually write a
function to copy
the keys/values of a map into a container let say a vector.

Many thanks, in advance, for your help.


#include <string>
#include <iterator>
#include <boost/foreach.hpp>
#include <iostream>
#include <list>
#include <map>

typedef std::map<std::wstring,std::wstring> MyMapType;
typedef std::pair<std::wstring,std::wstring> MapPairType;

MyMapType MyMap;

template<typename U>
std::list<typename U::key_type> getKeys(U const &m)
{
   typedef std::pair<typename U::key_type,typename U::mapped_type>
PairType;

   std::list<typename U::key_type> tempList;
   BOOST_FOREACH(PairType const &i,m)
      tempList.push_back(i.first);
   return tempList;

}

int main()
{
   MyMap[L"one"] = L"Hello World";
   MyMap[L"two"] = L"Another string";

   std::list<std::wstring> myList = getKeys(MyMap);

   BOOST_FOREACH(std::wstring &i,myList)
      std::wcout << i << L"\n";

   return 0;

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Thank you.

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