Eroare de compilare: user.cpp: In function ‘int main()’: user.cpp:85:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < vec.size(); ++i) ^ 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&, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<Elem*, std::vector<Elem> >; _Tp = Elem; _Compare = bool (*)(Elem&, Elem&)]’: /usr/include/c++/4.8/bits/stl_algo.h:2319:78: required from ‘_RandomAccessIterator std::__unguarded_partition_pivot(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<Elem*, std::vector<Elem> >; _Compare = bool (*)(Elem&, Elem&)]’ /usr/include/c++/4.8/bits/stl_algo.h:2360:62: required from ‘void std::__introsort_loop(_RandomAccessIterator, _RandomAccessIterator, _Size, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<Elem*, std::vector<Elem> >; _Size = int; _Compare = bool (*)(Elem&, Elem&)]’ /usr/include/c++/4.8/bits/stl_algo.h:5513:44: required from ‘void std::sort(_RAIter, _RAIter, _Compare) [with _RAIter = __gnu_cxx::__normal_iterator<Elem*, std::vector<Elem> >; _Compare = bool (*)(Elem&, Elem&)]’ user.cpp:83:38: required from here /usr/include/c++/4.8/bits/stl_algo.h:2287:35: error: invalid initialization of reference of type ‘Elem&’ from expression of type ‘const Elem’ while (__comp(*__first, __pivot)) ^ /usr/include/c++/4.8/bits/stl_algo.h:2290:34: error: invalid initialization of reference of type ‘Elem&’ from expression of type ‘const Elem’ while (__comp(__pivot, *__last)) ^