\\\\u005C (C99)\U00005C (C99)\\\x5C (encoding-dependent)\134 (encoding-dependent)??/ (until C23)\u{5C} (C++23)\x{5C} (C++23, encoding-dependent)\o{134} (C++23, encoding-dependent)\\\U0000005C\u005C\x5C (encoding-dependent)\134 (encoding-dependent)\\\u005C\u{5C}\u005C\\\x5C\5C\00005C=5C%5C