D. "c:\\user\\text.txt为什么不对

在C语言中，反斜杠（\）被用作转义字符，用于表示一些特殊字符。例如，\n表示换行符，\t表示制表符。因此，如果你想在字符串中使用反斜杠本身，你需要使用两个反斜杠（\\）来表示。

在你提供的路径字符串中，你使用了单个反斜杠（\）来表示路径分隔符。这会导致编译器将反斜杠后面的字符解释为转义字符，而不是普通字符。因此，你需要将路径字符串中的单个反斜杠（\）替换为两个反斜杠（\\），以正确表示路径。

正确的路径字符串应该是："c:\\user\\text.txt"。

请注意，这只是在C语言中表示字符串中的反斜杠的方法。在实际的文件路径中，你只需要使用一个反斜杠（\）来表示路径分隔符。

你还可以使用正斜杠（/）作为路径分隔符，因为在大多数操作系统中，正斜杠也被接受为路径分隔符。因此，你可以使用以下路径字符串之一来表示相同的路径：

"c:/user/text.txt"
"c:\\user\\text.txt"

相关问题

Q21: Which of the following is a valid user-defined output stream manipulator header? a. ostream& tab( ostream& output ) b. ostream tab( ostream output ) c. istream& tab( istream output ) d. void tab( ostream& output ) Q22: What will be output by the following statement? cout << showpoint << setprecision(4) << 11.0 << endl; a. 11 b. 11.0 c. 11.00 d. 11.000 Q23: Which of the following stream manipulators causes an outputted number’s sign to be left justified, its magnitude to be right justified and the center space to be filled with fill characters? a. left b. right c. internal d. showpos Q24: Which of the following statements restores the default fill character? a. cout.defaultFill(); b. cout.fill(); c. cout.fill( 0 ); d. cout.fill( ' ' ); Q25: When the showbase flag is set: a. The base of a number precedes it in brackets. b. Decimal numbers are not output any differently. c. "oct" or "hex" will be displayed in the output stream. d. Octal numbers can appear in one of two ways. Q26: What will be output by the following statements? double x = .0012345; cout << fixed << x << endl; cout << scientific << x << endl; a. 1.234500e-003 0.001235 b. 1.23450e-003 0.00123450 c. .001235 1.234500e-003 d. 0.00123450 1.23450e-003 Q27: Which of the following outputs does not guarantee that the uppercase flag has been set? a. All hexadecimal numbers appear in the form 0X87. b. All numbers written in scientific notation appear the form 6.45E+010. c. All text outputs appear in the form SAMPLE OUTPUT. d. All hexadecimal numbers appear in the form AF6. Q28: Which of the following is not true about bool values and how they're output with the output stream? a. The old style of representing true/false values used -1 to indicate false and 1 to indicate true. b. A bool value outputs as 0 or 1 by default. c. Stream manipulator boolalpha sets the output stream to display bool values as the strings "true" and "false". d. Both boolalpha and noboolalpha are “sticky” settings.

A21: a. ostream& tab( ostream& output ) is a valid user-defined output stream manipulator header.

A22: c. 11.00 will be output by the statement.

A23: c. internal is the stream manipulator that causes an outputted number’s sign to be left justified, its magnitude to be right justified and the center space to be filled with fill characters.

A24: d. cout.fill(' ') restores the default fill character, which is a space.

A25: c. "oct" or "hex" will be displayed in the output stream when the showbase flag is set.

A26: b. 1.23450e-003 and 1.23450e-003 will be output by the statements.

A27: d. All hexadecimal numbers appearing in the form AF6 does not guarantee that the uppercase flag has been set.

A28: a. The old style of representing true/false values used -1 to indicate false and 1 to indicate true is not true. False is represented by 0 and true is represented by any non-zero value.

以下关于示例 HTTP 报文的描述中，哪一项是错误的？ 示例： POST /index.html HTTP/1.1 Host: www.example.com:81 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:89.0) Gecko/20100101 Firefox/89.0 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8 Accept-Language: en-US,en;q=0.5 Accept-Encoding: gzip, deflate DNT: 1 Connection: close Cookie: SID=sksjdjojf98n3jnksd; Upgrade-Insecure-Requests: 1 username=amdin&password=admin A. JavaScript 可以操纵对应网站的 cookie 信息 B. 访问的域名是www.example.com C. User-Agent 是浏览器客户端自动生成，不能伪造 D. 该报文代表的含义是用户登录

选项 A、B、C 都是正确的，选项 D 是错误的。

A. JavaScript 可以操纵对应网站的 cookie 信息：JavaScript 可以通过 document.cookie 属性获取和修改当前网页的 cookie 信息，可以进行 cookie 劫持等攻击。

B. 访问的域名是 www.example.com：Host 头字段指定了请求的目标主机名和端口号，即 www.example.com:81，因此访问的域名是 www.example.com。

C. User-Agent 是浏览器客户端自动生成，不能伪造：User-Agent 是客户端发送请求时自动生成的标识字符串，可以通过伪造 User-Agent 字符串来欺骗服务器，例如伪装成某种浏览器或爬虫。

D. 该报文代表的含义是用户登录：该报文中并没有明确表示用户登录的信息，只是在报文的最后添加了一个参数 username=admin&password=admin。该参数可能是用于模拟用户登录的测试数据或者其他用途。因此，选项 D 是错误的。

因此，选项 A、B、C 都是正确的，选项 D 是错误的。