Eroare de compilare: user.cpp: In function ‘void back()’: user.cpp:13:14: error: no match for ‘operator<<’ (operand types are ‘std::ifstream {aka std::basic_ifstream<char>}’ and ‘int’) fout << st[i]; ^ user.cpp:13:14: note: candidates are: In file included from /usr/include/c++/4.8/string:52:0, from /usr/include/c++/4.8/bits/locale_classes.h:40, from /usr/include/c++/4.8/bits/ios_base.h:41, from /usr/include/c++/4.8/ios:42, from /usr/include/c++/4.8/istream:38, from /usr/include/c++/4.8/fstream:38, from user.cpp:1: /usr/include/c++/4.8/bits/basic_string.h:2753:5: note: template<class _CharT, class _Traits, class _Alloc> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const std::basic_string<_CharT, _Traits, _Alloc>&) operator<<(basic_ostream<_CharT, _Traits>& __os, ^ /usr/include/c++/4.8/bits/basic_string.h:2753:5: note: template argument deduction/substitution failed: user.cpp:13:21: note: ‘std::ifstream {aka std::basic_ifstream<char>}’ is not derived from ‘std::basic_ostream<_CharT, _Traits>’ fout << st[i]; ^ In file included from /usr/include/c++/4.8/istream:39:0, from /usr/include/c++/4.8/fstream:38, from user.cpp:1: /usr/include/c++/4.8/ostream:471:5: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, _CharT) operator<<(basic_ostream<_CharT, _Traits>& __out, _CharT __c) ^ /usr/include/c++/4.8/ostream:471:5: note: template argument deduction/substitution failed: user.cpp:13:21: note: ‘std::ifstream {aka std::basic_ifstream<char>}’ is not derived from ‘std::basic_ostream<_CharT, _Traits>’ fout << st[i]; ^ In file included from /usr/include/c++/4.8/istream:39:0, from /usr/include/c++/4.8/fstream:38, from user.cpp:1: /usr/include/c++/4.8/ostream:476:5: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, char) operator<<(basic_ostream<_CharT, _Traits>& __out, char __c) ^ /usr/include/c++/4.8/ostream:476:5: note: template argument deduction/substitution failed: user.cpp:13:21: note: ‘std::ifstream {aka std::basic_ifstream<char>}’ is not derived from ‘std::basic_ostream<_CharT, _Traits>’ fout << st[i]; ^ In file included from /usr/include/c++/4.8/istream:39:0, from /usr/include/c++/4.8/fstream:38, from user.cpp:1: /usr/include/c++/4.8/ostream:482:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, char) operator<<(basic_ostream<char, _Traits>& __out, char __c) ^ /usr/include/c++/4.8/ostream:482:5: note: template argument deduction/substitution failed: user.cpp:13:21: note: ‘std::ifstream {aka std::basic_ifstream<char>}’ is not derived from ‘std::basic_ostream<char, _Traits>’ fout << st[i]; ^ In file included from /usr/include/c++/4.8/istream:39:0,