Compilare: user.cpp: In function ‘std::queue<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::deque<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > > infix2postfix(std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > >)’: user.cpp:68: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > getElements(std::string)’: user.cpp:132: warning: comparison between signed and unsigned integer expressions user.cpp:139: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:156: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result