Compilare: main.cpp: In function 'int factor()': main.cpp:27:22: warning: array subscript has type 'char' [-Wchar-subscripts] valx=val[s[k]]; ^ main.cpp: In function 'int main()': main.cpp:63:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<aux.size();i++) ~^~~~~~~~~~~ main.cpp:89:14: warning: array subscript has type 'char' [-Wchar-subscripts] val[a]=!val[a]; ^ main.cpp:89:22: warning: array subscript has type 'char' [-Wchar-subscripts] val[a]=!val[a]; ^