Eroare de compilare: user.cpp: In member function ‘const bool& Punct::operator<(const Punct&)’: user.cpp:15:47: warning: returning reference to temporary [-Wreturn-local-addr] return x < p.x || (x == p.x && y < p.y); ^ In file included from /usr/include/c++/4.8/algorithm:62:0, from user.cpp:2: /usr/include/c++/4.8/bits/stl_algo.h: In instantiation of ‘_RandomAccessIterator std::__unguarded_partition(_RandomAccessIterator, _RandomAccessIterator, const _Tp&) [with _RandomAccessIterator = Punct*; _Tp = Punct]’: /usr/include/c++/4.8/bits/stl_algo.h:2307:70: required from ‘_RandomAccessIterator std::__unguarded_partition_pivot(_RandomAccessIterator, _RandomAccessIterator) [with _RandomAccessIterator = Punct*]’ /usr/include/c++/4.8/bits/stl_algo.h:2338:54: required from ‘void std::__introsort_loop(_RandomAccessIterator, _RandomAccessIterator, _Size) [with _RandomAccessIterator = Punct*; _Size = int]’ /usr/include/c++/4.8/bits/stl_algo.h:5475:36: required from ‘void std::sort(_RAIter, _RAIter) [with _RAIter = Punct*]’ user.cpp:89:18: required from here /usr/include/c++/4.8/bits/stl_algo.h:2269:19: error: passing ‘const Punct’ as ‘this’ argument of ‘const bool& Punct::operator<(const Punct&)’ discards qualifiers [-fpermissive] while (__pivot < *__last) ^