Re: the FOREACH macro

From:

John L Fjellstad <john-newsYEAR@fjellstad.org>

Newsgroups:

comp.lang.c++.moderated

Date:

31 Dec 2006 13:41:32 -0500

Message-ID:

<87mz54wlqg.fsf@fjellstad.org>

irek.szczesniak@gmail.com writes:

Hi,

I would like to do something like this, which is the WISH case:

typedef map<int, double> hash;
hash a;
// ...
FOREACH(a, key, value, hash)
std::cout << key << "->" << value << "\n";

Would it be easier to use for_each()?

Something like this:
#########
#include <iostream>
#include <map>
#include <cstdlib>

struct PrintOut
{
private:
      int key_;

public:
      PrintOut( int key ) : key_(key) {}

      void operator() ( const std::pair<int, double>& p )
      {
            if (key_ == p.first)
                  std::cout << p.first << "->" << p.second << "\n";
      }
};

int
main()
{
      std::map<int, double> a;

      a.insert( std::make_pair<int,double>(0, 1.71) );
      a.insert( std::make_pair<int,double>(1, 3.14) );

      std::for_each( a.begin(), a.end(), PrintOut(1) );

      return EXIT_SUCCESS;
}
#########

--
John L. Fjellstad
web: http://www.fjellstad.org/ Quis custodiet ipsos custodes
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