Compilare: user.cpp: In function ‘int main()’: user.cpp:18:12: warning: array subscript has type ‘char’ [-Wchar-subscripts] fr[s[1]]++; ^ user.cpp:26:23: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(fr[s[j]]==0) ^ user.cpp:28:24: warning: array subscript has type ‘char’ [-Wchar-subscripts] fr[s[j]]++; ^ user.cpp:32:24: warning: array subscript has type ‘char’ [-Wchar-subscripts] fr[s[j]]++; ^ user.cpp:42:20: warning: array subscript has type ‘char’ [-Wchar-subscripts] fr[s[i]]--; ^ user.cpp:43:23: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(fr[s[i]]==0) ^