Compilare: user.cpp: In function ‘int main()’: user.cpp:13:33: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (c[i] == ch && s[c[i]]) return fo << "NU\n",0; ^ user.cpp:14:36: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (c[i] != ch) if (!s[c[i]] || s[c[i]] == ch) s[c[i]] = ch;else return fo << "NU\n",0; ^ user.cpp:14:47: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (c[i] != ch) if (!s[c[i]] || s[c[i]] == ch) s[c[i]] = ch;else return fo << "NU\n",0; ^ user.cpp:14:62: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (c[i] != ch) if (!s[c[i]] || s[c[i]] == ch) s[c[i]] = ch;else return fo << "NU\n",0; ^ user.cpp:14:12: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if (c[i] != ch) if (!s[c[i]] || s[c[i]] == ch) s[c[i]] = ch;else return fo << "NU\n",0; ^ user.cpp:17:85: warning: array subscript has type ‘char’ [-Wchar-subscripts] for (int i='a';i<='z';++i) if (s[i]) fo << char(i) << ' ' << s[i] << '\n',s[s[i]] = 0; ^