Compilare: main.cpp: In function 'int main()': main.cpp:9:20: warning: array subscript has type 'char' [-Wchar-subscripts] if(f[s[i-1]][s[i]]){ ^ main.cpp:9:26: warning: array subscript has type 'char' [-Wchar-subscripts] if(f[s[i-1]][s[i]]){ ^ main.cpp:11:17: warning: array subscript has type 'char' [-Wchar-subscripts] f[s[i-1]][s[i]]=1; ^ main.cpp:11:23: warning: array subscript has type 'char' [-Wchar-subscripts] f[s[i-1]][s[i]]=1; ^