“退格"按钮转义字符"\ b":意外行为? [英] The "backspace" escape character '\b': unexpected behavior?

问题描述

所以我终于读完了 K& R ，我在第一篇中学到了一些东西几页，其中有一个退格转义字符\b.

So I'm finally reading through K&R, and I learned something within the first few pages, that there is a backspace escape character, \b.

所以我去测试一下，并且有一些非常奇怪的行为:

So I go to test it out, and there is some very odd behavior:

#include <stdio.h>

main ()
{
    printf("hello worl\b\bd\n");
}

输出为

hello wodl

有人可以解释吗?

推荐答案

根据您所使用的终端程序或控制台程序的类型，您的结果将有所不同，但是可以，大多数\b是 nondestructive 退格键.它将光标向后移动，但不会擦除其中的内容.

Your result will vary depending on what kind of terminal or console program you're on, but yes, on most \b is a nondestructive backspace. It moves the cursor backward, but doesn't erase what's there.

因此对于hello worl部分，代码将输出

So for the hello worl part, the code outputs

hello worl
          ^

...(其中^显示光标所在的位置)，然后输出两个\b字符，它们将光标向后移动两个位置而不会擦除(在您的终端上):

...(where ^ shows where the cursor is) Then it outputs two \b characters which moves the cursor backward two places without erasing (on your terminal):

hello worl
        ^

请注意，光标现在位于r上.然后输出d，覆盖r并给出:

Note the cursor is now on the r. Then it outputs d, which overwrites the r and gives us:

hello wodl
         ^

最后，它输出\n，这是非破坏性的换行符(同样，在大多数终端上，包括您的终端)，因此l保持不变，并且光标移至下一行的开头

Finally, it outputs \n, which is a non-destructive newline (again, on most terminals, including apparently yours), so the l is left unchanged and the cursor is moved to the beginning of the next line.

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