Eroare de compilare: user.cpp: In function ‘int main()’: user.cpp:55:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(index < questions.size()) { ^ user.cpp:57:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(index < questions.size() && questions[index].st == current_sum_index + 1) { ^ user.cpp:74:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(index < questions.size()) { ^ user.cpp:75:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(index < questions.size() && questions[index].S < current_sum) { ^ In file included from /usr/include/c++/4.8/algorithm:62:0, from /usr/include/i386-linux-gnu/c++/4.8/bits/stdc++.h:64, from user.cpp:1: /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<question*, std::vector<question> >; _Tp = question; _Compare = bool (*)(question&, question&)]’: /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<question*, std::vector<question> >; _Compare = bool (*)(question&, question&)]’ /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<question*, std::vector<question> >; _Size = int; _Compare = bool (*)(question&, question&)]’ /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<question*, std::vector<question> >; _Compare = bool (*)(question&, question&)]’ user.cpp:48:59: required from here /usr/include/c++/4.8/bits/stl_algo.h:2287:35: error: invalid initialization of reference of type ‘question&’ from expression of type ‘const question’ while (__comp(*__first, __pivot)) ^ /usr/include/c++/4.8/bits/stl_algo.h:2290:34: error: invalid initialization of reference of type ‘question&’ from expression of type ‘const question’ while (__comp(__pivot, *__last)) ^