Compilare: user.cpp: In function ‘void push_op_in_polo()’: user.cpp:28:31: warning: array subscript has type ‘char’ [-Wchar-subscripts] polo.push_back(id[op.top()]); ^ user.cpp: In function ‘int main()’: user.cpp:55:42: warning: array subscript has type ‘char’ [-Wchar-subscripts] while (!op.empty() && pr[s[i]] <= pr[op.top()]) push_op_in_polo(); ^ user.cpp:55:58: warning: array subscript has type ‘char’ [-Wchar-subscripts] while (!op.empty() && pr[s[i]] <= pr[op.top()]) push_op_in_polo(); ^ user.cpp:62:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < polo.size(); ++i) { ^ user.cpp:38:11: warning: array subscript is above array bounds [-Warray-bounds] id['+'] = -1; ^ user.cpp:39:11: warning: array subscript is above array bounds [-Warray-bounds] id['-'] = -2; ^ user.cpp:40:11: warning: array subscript is above array bounds [-Warray-bounds] id['*'] = -3; ^ user.cpp:41:11: warning: array subscript is above array bounds [-Warray-bounds] id['/'] = -4; ^