Compilare: main.cpp: In function 'int main()': main.cpp:18:16: warning: array subscript has type 'char' [-Wchar-subscripts] fr[x[j]]++; ^ main.cpp:19:20: warning: array subscript has type 'char' [-Wchar-subscripts] if (fr[x[j]] == 1) ++contor; ^ main.cpp:22:22: warning: array subscript has type 'char' [-Wchar-subscripts] --fr[x[i]]; ^ main.cpp:23:24: warning: array subscript has type 'char' [-Wchar-subscripts] if (fr[x[i]] == 0) --contor; ^