Compilare: user.cpp: In function ‘int main()’: user.cpp:29:13: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(c[a[i]] == 0) ^ user.cpp:30:11: warning: array subscript has type ‘char’ [-Wchar-subscripts] c[a[i]] = b[i]; ^ user.cpp:32:13: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(c[a[i]] != b[i]) ^