Compilare: user.cpp: In function ‘int main()’: user.cpp:17:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s1.size(); i++) ^ user.cpp:19:20: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (v[s1[i]] == 0) ^ user.cpp:20:20: warning: array subscript has type ‘char’ [-Wchar-subscripts] v[s1[i]] = s2[i]; ^ user.cpp:22:24: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (v[s1[i]] != s2[i]) ^