Eroare de compilare: In file included from /usr/include/c++/4.8/algorithm:62:0, from user.cpp:4: /usr/include/c++/4.8/bits/stl_algo.h: In instantiation of ‘_RandomAccessIterator std::__unguarded_partition(_RandomAccessIterator, _RandomAccessIterator, const _Tp&, _Compare) [with _RandomAccessIterator = 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 = 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 = 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 = elem*; _Compare = bool (*)(elem&, elem&)]’ user.cpp:40:32: 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)) ^