Compilare: user.cpp: In function ‘int main()’: user.cpp:24:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < expr.size (); ++i) ^ user.cpp:30:62: warning: array subscript has type ‘char’ [-Wchar-subscripts] while (!semn.empty () && p[semn[semn.size () - 1]] >= p[expr[i]]) ^ user.cpp:30:76: warning: array subscript has type ‘char’ [-Wchar-subscripts] while (!semn.empty () && p[semn[semn.size () - 1]] >= p[expr[i]]) ^ user.cpp:43:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < eval.size (); ++i) ^ user.cpp:55:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < ss.size (); ++i) ^