Compilare: user.cpp: In function ‘int main()’: user.cpp:18:17: warning: array subscript has type ‘char’ [-Wchar-subscripts] fr[s[dr]]++; ^ user.cpp:19:21: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (fr[s[dr]]==1) ^ user.cpp:22:28: warning: array subscript has type ‘char’ [-Wchar-subscripts] while (fr[s[st]]>1) ^ user.cpp:24:25: warning: array subscript has type ‘char’ [-Wchar-subscripts] fr[s[st]]--; ^ user.cpp:27:19: warning: array subscript has type ‘char’ [-Wchar-subscripts] fr[s[st]]--; st++;nr--; ^