Eroare de compilare: user.cpp: In function ‘int main()’: user.cpp:16:7: error: no match for ‘operator<<’ (operand types are ‘std::ifstream {aka std::basic_ifstream<char>}’ and ‘int’) fout << a + b; ^ user.cpp:16:7: note: candidates are: In file included from /usr/include/c++/4.8/istream:39:0, from /usr/include/c++/4.8/fstream:38, from user.cpp:3: /usr/include/c++/4.8/ostream:602:5: note: template<class _CharT, class _Traits, class _Tp> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&&, const _Tp&) operator<<(basic_ostream<_CharT, _Traits>&& __os, const _Tp& __x) ^ /usr/include/c++/4.8/ostream:602:5: note: template argument deduction/substitution failed: user.cpp:16:14: note: ‘std::ifstream {aka std::basic_ifstream<char>}’ is not derived from ‘std::basic_ostream<_CharT, _Traits>’ fout << a + b; ^ In file included from /usr/include/c++/4.8/istream:39:0, from /usr/include/c++/4.8/fstream:38, from user.cpp:3: /usr/include/c++/4.8/ostream:548:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const unsigned char*) operator<<(basic_ostream<char, _Traits>& __out, const unsigned char* __s) ^ /usr/include/c++/4.8/ostream:548:5: note: template argument deduction/substitution failed: user.cpp:16:14: note: ‘std::ifstream {aka std::basic_ifstream<char>}’ is not derived from ‘std::basic_ostream<char, _Traits>’ fout << a + b; ^ In file included from /usr/include/c++/4.8/istream:39:0, from /usr/include/c++/4.8/fstream:38, from user.cpp:3: /usr/include/c++/4.8/ostream:543:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const signed char*) operator<<(basic_ostream<char, _Traits>& __out, const signed char* __s) ^ /usr/include/c++/4.8/ostream:543:5: note: template argument deduction/substitution failed: user.cpp:16:14: note: ‘std::ifstream {aka std::basic_ifstream<char>}’ is not derived from ‘std::basic_ostream<char, _Traits>’ fout << a + b; ^ In file included from /usr/include/c++/4.8/istream:39:0, from /usr/include/c++/4.8/fstream:38, from user.cpp:3: /usr/include/c++/4.8/ostream:530:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const char*) operator<<(basic_ostream<char, _Traits>& __out, const char* __s) ^ /usr/include/c++/4.8/ostream:530:5: note: template argument deduction/substitution failed: user.cpp:16:14: note: ‘std::ifstream {aka std::basic_ifstream<char>}’ is not derived from ‘std::basic_ostream<char, _Traits>’ fout << a + b; ^ In file included from /usr/include/c++/4.8/ostream:609:0, from /usr/include/c++/4.8/istream:39, from /usr/include/c++/4.8/fstream:38, from user.cpp:3: /usr/include/c++/4.8/bits/ostream.tcc:321:5: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const char*)