请解释这种意外的\ b(退格)行为 [英] Please explain this unexpected \b (backspace) behavior

问题描述

预期:

>>> print "I print\b\b Backspace\b\b!"
I pri Backspa!
>>> print "I print\b\b Backspace\b\b\b!"
I pri Backsp!

已观察:

>>> print "I print\b\b Backspace\b\b!"
I pri Backspa!e
>>> print "I print\b\b Backspace\b\b\b!"
I pri Backsp!ce

为什么不删除'e'和'ce'和'！'插入了吗?

Why does is 'e' and 'ce' not erased and '!' inserted?

推荐答案

\ b 也称为退格，将光标向后移动1.

The \b also termed as back space moves back the cursor by 1.

退格键不会删除任何内容，它会将光标移到左侧，并且随后的内容将其覆盖.

The backspace doesn't delete anything, it moves the cursor to the left and it gets covered up by what you write afterwards.

让我们通过您的示例来理解这一点:

Let's understand this with your example:

"I print\b\b Backspace\b\b!"    # original string passed to "print"
#     ^^ * *        ^^ * *
#     12 1 2        34 3 4

• 执行 * 1 和 * 2 后，光标移至 ^ 1 .因此， ^ 1 被空格''替换，而 ^ 2 被 B 替换(之后的字符\ b )

  • After executing *1 and *2, cursor comes at ^1. Hence, ^1 is replaced by space ' ' and ^2 replaced by B (characters following \b)

    在执行 * 3 和 * 4 之后，光标位于 ^ 3 处，并被！.由于！之后没有任何内容，因此 ^ 4 保持原样，否则将被下一个字符替换.

    After executing *3, and *4, cursor comes at ^3 and is replaced by !. Since there was nothing after !, ^4 remains as it is, else would have be replaced by the next character.

    因此，打印在屏幕上的结果内容如下:

    Hence the resultant content that is printed on the screen is as:

    I pri Backspa!e
    

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