/* Code for exercise 20.5. |  | "C++ Solutions--Companion to The C++ Programming Language, Third Edition" | by David Vandevoorde; Addison-Wesley 1998; ISBN 0-201-30965-3. | | Permission to use, copy, modify, distribute and sell this software | and its documentation for any purpose is hereby granted without fee. | The author makes no representations about the suitability of this | software for any purpose.  It is provided "as is" without express or | implied warranty. `----------------------------------------------------------------------*/#include <algorithm>#include <iostream>#include <iterator>#include <string>template<typename C, typename T, typename A>struct string_appender   : std::iterator<std::output_iterator_tag, void, void, void, void> {   typedef std::basic_string<C, T, A> string;   typedef typename string::value_type value_type;   explicit string_appender(string &s): s_(s) {}   string_appender& operator=(value_type const &ch) {      s_.append(1, ch);      return *this;   }   string_appender& operator*() { return *this; }   string_appender const& operator*() const { return *this; }   string_appender& operator++() { return *this; }   string_appender operator++(int) { return *this; }private:   std::string &s_;};template<typename C, typename T, typename A> inlinestring_appender<C, T, A>back_inserter(std::basic_string<C, T, A> &s) {   return string_appender<C, T, A>(s);}char const apx[] = "-appendix";int main() {   std::string book("preface");   std::copy(&apx[0], &apx[0]+sizeof(apx), back_inserter(book));   std::cout << book << '\n';   return 0;}