Compilare: user.cpp: In function ‘int main()’: user.cpp:18:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < s1.size(); ++i){ ^ user.cpp:19:25: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(mapping[s1[i]] && mapping[s1[i]] != s2[i]){ ^ user.cpp:19:43: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(mapping[s1[i]] && mapping[s1[i]] != s2[i]){ ^ user.cpp:22:22: warning: array subscript has type ‘char’ [-Wchar-subscripts] mapping[s1[i]] = s2[i]; } ^