Compilare: user.cpp: In function ‘void do_a_cycle()’: user.cpp:13:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < viable.size() && !found; ++i){ ^ user.cpp:14:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = 0; j < viable.size() && !found; ++j){ ^ user.cpp:15:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(k = 0; k < viable.size() && !found; ++k){ ^ user.cpp:28:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < viable.size(); ++i){ ^ user.cpp:34:44: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0, k = 1; j < cur_ciclu.size() && ! done; ++j, ++k){ ^ user.cpp:35:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(k == cur_ciclu.size()){ ^ user.cpp:42:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i_other = 0; i_other < viable.size() && !done; ++i_other){ ^ user.cpp:46:45: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0, k = 1; j < cur_ciclu.size() && !done; ++j, ++k){ ^ user.cpp:47:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(k == cur_ciclu.size()){ ^