Ассоциативные контейнеры

#include <iostream>
#include <fstream>
#include <iterator>
#include <algorithm>
#include <string>
#include <set>
 
int main()
{
    typedef std::istream_iterator<std::string> string_in_iter_t;
    typedef std::ostream_iterator<std::string> string_out_iter_t;
    // ----------
 
    const char* filename = "file.txt";
    std::ifstream in_file(filename);
 
    if(!in_file.is_open())
    {
        std::cerr << "can`t open file \"" << filename << "\"\n";
        return 1;
    }
 
    std::set<std::string> s(string_in_iter_t(in_file), (string_in_iter_t()));
    std::copy(s.begin(), s.end(), string_out_iter_t(std::cout, "\n"));
}

#include <iostream>
#include <fstream>
#include <string>
#include <map>
 
int main()
{
    const char* filename = "file.txt";
    std::ifstream in_file(filename);
 
    if(!in_file.is_open())
    {
        std::cerr << "can`t open file \"" << filename << "\"\n";
        return 1;
    }
 
    std::map<std::string, int> m;
 
    std::string token;
    while(in_file >> token)
        ++m[token];
 
    for(std::map<std::string, int>::iterator iter = m.begin(); iter != m.end(); ++iter)
        std::cout << iter->first << " -> " << iter->second << '\n';
}