#include <algorithm>
#include <iostream>
#include <iterator>
#include <map>
#include <sstream>
 
struct Counter
{
    std::map<std::string, int> wordCount;
    void operator()(const std::string & item) { ++wordCount[item]; }
    operator std::map<std::string, int>() { return wordCount; }
};
 
 
int main()
{
    std::string input =
        "Relations between data in the STL are represented with maps."
        "A map is a directed relation, by using it you are representing "
        "a mapping. In this directed relation, the first type is related to "
        "the second type but it is not true that the inverse relationship "
        "holds. This is useful in a lot of situations, but there are some "
        "relationships that are bidirectional by nature.";
 
     std::istringstream instream (input);
 
     std::istream_iterator<std::string> start(instream);
     std::istream_iterator<std::string> end;
 
     std::map<std::string, int> wordCount = std::for_each(start, end, Counter());
 
     for (std::map<std::string, int>::iterator it = wordCount.begin(); it != wordCount.end(); ++it)
     {
          std::cout << it->first <<" : "<< it->second << std::endl;
     }
 }

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