Compilare: main.cpp: In function 'int main()': main.cpp:14:23: warning: array subscript has type 'char' [-Wchar-subscripts] if ( fr[s[i-1]][s[i]] ) ^ main.cpp:14:29: warning: array subscript has type 'char' [-Wchar-subscripts] if ( fr[s[i-1]][s[i]] ) ^ main.cpp:16:18: warning: array subscript has type 'char' [-Wchar-subscripts] fr[s[i-1]][s[i]]++; ^ main.cpp:16:24: warning: array subscript has type 'char' [-Wchar-subscripts] fr[s[i-1]][s[i]]++; ^