Eroare de compilare: user.cpp: In function ‘int main()’: user.cpp:49:9: error: no match for ‘operator<’ (operand types are ‘std::ofstream {aka std::basic_ofstream<char>}’ and ‘const char [6]’) fout<"jflg\n"; ~~~~^~~~~~~~~ In file included from /usr/include/c++/6/bits/stl_algobase.h:64:0, from /usr/include/c++/6/bits/char_traits.h:39, from /usr/include/c++/6/ios:40, from /usr/include/c++/6/istream:38, from /usr/include/c++/6/fstream:38, from user.cpp:1: /usr/include/c++/6/bits/stl_pair.h:441:5: note: candidate: template<class _T1, class _T2> constexpr bool std::operator<(const std::pair<_T1, _T2>&, const std::pair<_T1, _T2>&) operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y) ^~~~~~~~ /usr/include/c++/6/bits/stl_pair.h:441:5: note: template argument deduction/substitution failed: user.cpp:49:10: note: ‘std::ofstream {aka std::basic_ofstream<char>}’ is not derived from ‘const std::pair<_T1, _T2>’ fout<"jflg\n"; ^~~~~~~~ In file included from /usr/include/c++/6/bits/stl_algobase.h:67:0, from /usr/include/c++/6/bits/char_traits.h:39, from /usr/include/c++/6/ios:40, from /usr/include/c++/6/istream:38, from /usr/include/c++/6/fstream:38, from user.cpp:1: /usr/include/c++/6/bits/stl_iterator.h:298:5: note: candidate: template<class _Iterator> bool std::operator<(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_Iterator>&) operator<(const reverse_iterator<_Iterator>& __x, ^~~~~~~~ /usr/include/c++/6/bits/stl_iterator.h:298:5: note: template argument deduction/substitution failed: user.cpp:49:10: note: ‘std::ofstream {aka std::basic_ofstream<char>}’ is not derived from ‘const std::reverse_iterator<_Iterator>’ fout<"jflg\n"; ^~~~~~~~ In file included from /usr/include/c++/6/bits/stl_algobase.h:67:0, from /usr/include/c++/6/bits/char_traits.h:39, from /usr/include/c++/6/ios:40, from /usr/include/c++/6/istream:38, from /usr/include/c++/6/fstream:38, from user.cpp:1: /usr/include/c++/6/bits/stl_iterator.h:355:5: note: candidate: template<class _IteratorL, class _IteratorR> bool std::operator<(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_IteratorR>&) operator<(const reverse_iterator<_IteratorL>& __x, ^~~~~~~~ /usr/include/c++/6/bits/stl_iterator.h:355:5: note: template argument deduction/substitution failed: user.cpp:49:10: note: ‘std::ofstream {aka std::basic_ofstream<char>}’ is not derived from ‘const std::reverse_iterator<_Iterator>’ fout<"jflg\n"; ^~~~~~~~ In file included from /usr/include/c++/6/bits/stl_algobase.h:67:0, from /usr/include/c++/6/bits/char_traits.h:39, from /usr/include/c++/6/ios:40, from /usr/include/c++/6/istream:38, from /usr/include/c++/6/fstream:38, from user.cpp:1: /usr/include/c++/6/bits/stl_iterator.h:1137:5: note: candidate: template<class _IteratorL, class _IteratorR> bool std::operator<(const std::move_iterator<_IteratorL>&, const std::move_iterator<_IteratorR>&)