Chapter 10. Expressions | 10.2 A Desk Calculator | 10.2.3 Low-Level Input

Token_stream::get()的定义当中处理标识符的一段代码有错误：
default:    // NAME, NAME=, or error
    if (isalpha(ch)) {
        string_value = ch;
        while (ip–>get(ch) && isalnum(ch))
            string_value += ch; // append ch to end of string_value
        ip–>putback(ch);
        return ct={Kind::name};
    }

应该改为：
default:
    if (isalpha(ch)) {
        ct.string_value = ch;
	while (ip->get(ch) && isalnum(ch))
	    ct.string_value += ch;
	ip->putback(ch);
	ct.kind = Kind::name;
	return ct;
    }