Compilare: user.cpp: In function ‘int main()’: user.cpp:18:29: warning: array subscript has type ‘char’ [-Wchar-subscripts] for(i=1;i<=n;++i) ++fr[s[i]]; ^ user.cpp:22:13: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(fr[s[i]]==0) continue; ^ user.cpp:27:29: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(s[i]<bestch && fr[s[i]]) { ^ user.cpp:32:14: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(fr[s[i]]==1) break; ^ user.cpp:33:13: warning: array subscript has type ‘char’ [-Wchar-subscripts] --fr[s[i]]; ^ user.cpp:39:13: warning: array subscript has type ‘char’ [-Wchar-subscripts] ++fr[s[i]]; ^ user.cpp:43:12: warning: array subscript has type ‘char’ [-Wchar-subscripts] fr[bestch]=0; ^