Compilare: user.cpp: In function ‘void prec_()’: user.cpp:45:9: warning: array subscript has type ‘char’ [-Wchar-subscripts] ok[a] = ok[a ^ 0x20] = true; ^ user.cpp: In function ‘void input()’: user.cpp:52:17: warning: array subscript has type ‘char’ [-Wchar-subscripts] for (; ok[*cur]; ++cur); ^ user.cpp:54:18: warning: array subscript has type ‘char’ [-Wchar-subscripts] for (; !ok[*cur]; ++cur); ^ user.cpp:56:17: warning: array subscript has type ‘char’ [-Wchar-subscripts] for (; ok[*cur]; ++cur); ^