Compilare: user.cpp: In function ‘bool ok()’: user.cpp:15:21: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (_stack[i] == _stack[vf]) ^ user.cpp:15:35: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (_stack[i] == _stack[vf]) ^ user.cpp: In function ‘void print()’: user.cpp:23:24: warning: array subscript has type ‘char’ [-Wchar-subscripts] out << _stack[i] << " "; ^ user.cpp: In function ‘int main()’: user.cpp:33:16: warning: array subscript has type ‘char’ [-Wchar-subscripts] _stack[++vf] = '0'; ^ user.cpp:36:18: warning: array subscript has type ‘char’ [-Wchar-subscripts] _stack[vf]++; ^ user.cpp:37:22: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (_stack[vf] > N) ^ user.cpp:46:32: warning: array subscript has type ‘char’ [-Wchar-subscripts] _stack[++vf] = '0'; ^