Compilare: user.cpp: In function ‘int main()’: user.cpp:14:11: warning: array subscript has type ‘char’ [-Wchar-subscripts] fr[ch]++; ^ user.cpp:18:14: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(fr[ch]!=0) ^ user.cpp:25:12: warning: array subscript has type ‘char’ [-Wchar-subscripts] c[a[i]]=x; ^ user.cpp:39:17: warning: array subscript has type ‘char’ [-Wchar-subscripts] st=i-c[b[i]]; ^ user.cpp:42:14: warning: array subscript has type ‘char’ [-Wchar-subscripts] dr=i+c[b[i]]; ^