Compilare: main.cpp: In function 'int main()': main.cpp:25:30: warning: array subscript has type 'char' [-Wchar-subscripts] t.push_back('('); ^ main.cpp:37:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] { if(t[i] == '(') { if(t[i-1] == '+' || t[i-1] == '(') stiva.push(1); ~^~~~~~~~~ main.cpp:47:23: warning: array subscript has type 'char' [-Wchar-subscripts] for(int i='a'; i<='z'; i++) ^ main.cpp:47:33: warning: array subscript has type 'char' [-Wchar-subscripts] for(int i='a'; i<='z'; i++) ^