Compilare: main.cpp: In function 'int main()': main.cpp:14:8: warning: array subscript has type 'char' [-Wchar-subscripts] fr[ch]++; ^ main.cpp:18:12: warning: array subscript has type 'char' [-Wchar-subscripts] if (fr[ch] != 0) ^ main.cpp:25:9: warning: array subscript has type 'char' [-Wchar-subscripts] c[a[i]] = x; ^ main.cpp:39:18: warning: array subscript has type 'char' [-Wchar-subscripts] st = i - c[b[i]]; ^ main.cpp:42:18: warning: array subscript has type 'char' [-Wchar-subscripts] dr = i + c[b[i]]; ^