Eroare de compilare: main.cpp: In function 'int main()': main.cpp:24:14: error: no match for 'operator!=' (operand types are 'std::ifstream {aka std::basic_ifstream<char>}' and 'long int') if (input!=NULL) ^ main.cpp:24:14: note: candidate: operator!=(int, long int) <built-in> main.cpp:24:14: note: no known conversion for argument 1 from 'std::ifstream {aka std::basic_ifstream<char>}' to 'int' In file included from /usr/include/c++/6/iosfwd:40:0, from /usr/include/c++/6/ios:38, from /usr/include/c++/6/ostream:38, from /usr/include/c++/6/iostream:39, from main.cpp:1: /usr/include/c++/6/bits/postypes.h:221:5: note: candidate: template<class _StateT> bool std::operator!=(const std::fpos<_StateT>&, const std::fpos<_StateT>&) operator!=(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs) ^~~~~~~~ /usr/include/c++/6/bits/postypes.h:221:5: note: template argument deduction/substitution failed: In file included from /usr/include/_G_config.h:15:0, from /usr/include/libio.h:31, from /usr/include/stdio.h:74, from /usr/include/c++/6/cstdio:42, from /usr/include/c++/6/ext/string_conversions.h:43, from /usr/include/c++/6/bits/basic_string.h:5420, from /usr/include/c++/6/string:52, from /usr/include/c++/6/bits/locale_classes.h:40, from /usr/include/c++/6/bits/ios_base.h:41, from /usr/include/c++/6/ios:42, from /usr/include/c++/6/ostream:38, from /usr/include/c++/6/iostream:39, from main.cpp:1: main.cpp:24:16: note: 'std::ifstream {aka std::basic_ifstream<char>}' is not derived from 'const std::fpos<_StateT>' if (input!=NULL) ^ 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/ostream:38, from /usr/include/c++/6/iostream:39, from main.cpp:1: /usr/include/c++/6/bits/stl_pair.h:448:5: 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:448:5: note: template argument deduction/substitution failed: In file included from /usr/include/_G_config.h:15:0, from /usr/include/libio.h:31, from /usr/include/stdio.h:74, from /usr/include/c++/6/cstdio:42, from /usr/include/c++/6/ext/string_conversions.h:43, from /usr/include/c++/6/bits/basic_string.h:5420, from /usr/include/c++/6/string:52, from /usr/include/c++/6/bits/locale_classes.h:40, from /usr/include/c++/6/bits/ios_base.h:41, Non zero exit status: 1