Python 扩展标签长度计算 [英] Python Expand Tabs Length Calculation
问题描述
我对使用 expandtabs 时如何计算字符串长度感到困惑.我认为 expandtabs 用适当数量的空格替换制表符(每个制表符的默认空格数为 8).然而，当我使用不同长度的字符串和不同数量的选项卡运行命令时，长度计算与我想象的不同(即，每个选项卡并不总是导致每个实例的字符串长度增加 8/t").
I'm confused by how the length of a string is calculated when expandtabs is used. I thought expandtabs replaces tabs with the appropriate number of spaces (with the default number of spaces per tab being 8). However, when I ran the commands using strings of varying lengths and varying numbers of tabs, the length calculation was different than I thought it would be (i.e., each tab didn't always result in the string length being increased by 8 for each instance of "/t").
下面是一个详细的脚本输出，带有注释，解释了我认为上面执行的命令的结果.有人可以解释一下使用展开标签时如何计算长度吗?
Below is a detailed script output with comments explaining what I thought should be the result of the command executed above. Would someone please explain the how the length is calculated when expand tabs is used?
IDLE 2.6.5
>>> s = '\t'
>>> print len(s)
1
>>> #the length of the string without expandtabs was one (1 tab counted as a single space), as expected.
>>> print len(s.expandtabs())
8
>>> #the length of the string with expandtabs was eight (1 tab counted as eight spaces).
>>> s = '\t\t'
>>> print len(s)
2
>>> #the length of the string without expandtabs was 2 (2 tabs, each counted as a single space).
>>> print len(s.expandtabs())
16
>>> #the length of the string with expandtabs was 16 (2 tabs counted as 8 spaces each).
>>> s = 'abc\tabc'
>>> print len(s)
7
>>> #the length of the string without expandtabs was seven (6 characters and 1 tab counted as a single space).
>>> print len(s.expandtabs())
11
>>> #the length of the string with expandtabs was NOT 14 (6 characters and one 8 space tabs).
>>> s = 'abc\tabc\tabc'
>>> print len(s)
11
>>> #the length of the string without expandtabs was 11 (9 characters and 2 tabs counted as a single space).
>>> print len(s.expandtabs())
19
>>> #the length of the string with expandtabs was NOT 25 (9 characters and two 8 space tabs).
>>>
推荐答案
就像在文本编辑器中输入制表符一样，制表符会将长度增加到 8 的下一个倍数.
Like when you are entering tabs in a text-editor, the tab character increases the length to the next multiple of 8.
所以:
'\t'显然是 8.'\t\t'是 16.'abc\tabc'从 3 个字符开始，然后一个制表符将它推到 8，然后最后一个'abc'将它从 8 推到 11...'abc\tabc\tabc'同样从 3 开始，制表符将其推到 8，另一个'abc'转到 11，然后另一个制表符将其推到 16，最后的'abc'将长度变为 19.
'\t'by itself is 8, obviously.'\t\t'is 16.'abc\tabc'starts at 3 characters, then a tab pushes it up to 8, and then the last'abc'pushes it from 8 to 11...'abc\tabc\tabc'likewise starts at 3, tab bumps it to 8, another'abc'goes to 11, then another tab pushes it to 16, and the final'abc'brings the length to 19.
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