Compilare: user.cpp: In function ‘int main()’: user.cpp:69:45: warning: array subscript has type ‘char’ [-Wchar-subscripts] while(!op.empty() && priority[ch] <= priority[op.top()]) ^ user.cpp:69:67: warning: array subscript has type ‘char’ [-Wchar-subscripts] while(!op.empty() && priority[ch] <= priority[op.top()]) ^