Compilare: user.cpp: In function ‘int main()’: user.cpp:15:10: warning: array subscript has type ‘char’ [-Wchar-subscripts] f[s[0]]++; nr++; ^ user.cpp:22:20: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (f[s[j]] == 0) ^ user.cpp:24:19: warning: array subscript has type ‘char’ [-Wchar-subscripts] f[s[j]]++; ^ user.cpp:27:21: warning: array subscript has type ‘char’ [-Wchar-subscripts] else f[s[j]]++; ^ user.cpp:38:16: warning: array subscript has type ‘char’ [-Wchar-subscripts] f[s[i]]--; ^ user.cpp:39:21: warning: array subscript has type ‘char’ [-Wchar-subscripts] if ( f[s[i]] == 0 ) nr--; ^