c - "\b"在 gdb 字符串打印输出中意味着什么？

Question

当我在包含不可打印字符的缓冲区 buf 上发出命令 p buf 时，当 gdb 尝试打印不可打印字符时，我通常会得到八进制输出。

然而，这次我得到了这样一个字符串。

foobar\341\204\004\b\357\373\377\277

这里的\b是什么意思？

Answer 1

\b 是退格字符(\010 如果您使用的是 ASCII)。

以下是 C 标准定义的其余转义序列(5.2.2 字符显示语义):

2 Alphabetic escape sequences representing nongraphic characters in the execution character set are intended to produce actions on display devices as follows:

\a (alert) Produces an audible or visible alert without changing the active position.

\b (backspace) Moves the active position to the previous position on the current line. If the active position is at the initial position of a line, the behavior of the display device is unspecified.

\f (form feed) Moves the active position to the initial position at the start of the next logical page.

\n (new line) Moves the active position to the initial position of the next line.

\r (carriage return) Moves the active position to the initial position of the current line.

\t (horizontal tab) Moves the active position to the next horizontal tabulation position on the current line. If the active position is at or past the last defined horizontal tabulation position, the behavior of the display device is unspecified.

\v (vertical tab) Moves the active position to the initial position of the next vertical tabulation position. If the active position is at or past the last defined vertical tabulation position, the behavior of the display device is unspecified.