C++的一个好库。。。现在很流行

				Example
				.......
				
				::
				
				    struct string_appender
				    {
					string_appender(std::string& s)
					    : m_str(&s)
					{}
				
					void operator()(const std::string& x) const
					{
					    *m_str += x;
					}
				
					std::string* m_str;
				    };
				
				    int main(int, char*[])
				    {
				      std::vector x;
				      x.push_back("hello");
				      x.push_back(" ");
				      x.push_back("world");
				      x.push_back("!");
				
				      std::string s = "";
				      std::copy(x.begin(), x.end(), 
						boost::make_function_output_iterator(string_appender(s)));
				
				      std::cout 				
				      return 0;
				    }