使'交替輸出左引號、右引號

hbghlyj

直引號'在LaTeX中預設是右引號。在LaTeX中可以修改它，使它交替輸出左引號、右引號

1. \documentclass{article}
3. \newcount\quoteCount
4. \quoteCount=0
5. \let\rightquote='
6. \catcode`'=13 % Make ' an active character
7. \def'{%
8.     \ifodd\quoteCount
9.         \rightquote%
10.     \else
11.         `%
12.     \fi
13.     \advance\quoteCount by 1
14. }
16. \begin{document}
18. Hello, 'world'!
20. Hello, 'world'!
22. \end{document}

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效果：
Hello, ‘world’!
Hello, ‘world’!

上面用的是TeX counts，或者可以用LaTeX counter，它們的區別：texdev.net/2009/11/17/tex-counts-and-latex-counters/
需把\newcounter\quoteCount改為\newcounter{quoteCount}，把\iffodd\quoteCount改為\iffodd\value{quoteCount}，把\advance\quoteCount by 1改為\stepcounter{quoteCount}：

1. \documentclass{article}
3. \newcounter{quoteCount}
4. \let\rightquote='
5. \catcode`'=13 % Make ' an active character
6. \def'{%
7.     \ifodd\value{quoteCount}%
8.         \rightquote%
9.     \else
10.         `%
11.     \fi
12.     \stepcounter{quoteCount}%
13. }
15. \begin{document}
17. Hello, 'world'!
19. Hello, 'world'!
21. \end{document}

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Why choice one or other method? Well, LaTeX does error checking and also adds some refinements (such as resetting one counter based on another). It also ensures you always include the appropriate \relax statements to avoid TeX picking up ‘extra’ material for numbers. On the other hand, if you want to do local assignments then you have to use TeX’s count registers: LaTeX always does global assignments. I tend to find that for document-level things counters are best (anything I actually want to print), whereas count registers are more flexible for programming.

hbghlyj

可以避免設新的變量，把\let\rightquote='去除，舊的\rightquote改为\char39：

1. \documentclass{article}
3. \newcount\quoteCount
4. \quoteCount=0
5. \catcode`'=13 % Make ' an active character
6. \def'{%
7.     \ifodd\quoteCount
8.         \char39%
9.     \else
10.         `%
11.     \fi
12.     \advance\quoteCount by 1
13. }
15. \begin{document}
17. Hello, 'world'!
19. Hello, 'world'!
21. \end{document}

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這裡的39是用`查到的：

1. \documentclass{article}
2. \begin{document}
3. \number\numexpr`'
4. \end{document}

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kuing

1. \number\numexpr`'

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第一次见😃这招好

kuing

其实在英文文本中经常有纯单引号 's 之类的使用，所以使 ' 交替输出左右引号其实是不合适的。
这帖的意义纯粹是学习这种定义方式而已。

hbghlyj

kuing 发表于 2024-2-27 09:01
其实在英文文本中经常有纯单引号 's 之类的使用

apostrophe可以用 \textquotesingle
texlive.net/run?%5Cdocumentclass%7Barticle%7D … %5Cend%7Bdocument%7D

1. \documentclass{article}
2. \begin{document}
3.     `It\textquotesingle s a nice day!'
4. \end{document}

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kuing

1. \documentclass{article}
3. \catcode`'=13 % Make ' an active character
4. \def'{\lq\let\xxq\lq\let\lq\rq\let\rq\xxq}
6. \begin{document}
8. Hello, 'world'!
10. Hello, 'world'!
12. Hello, 'world'!
14. I'm fine!
16. Hello, 'world'!
18. \end{document}

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效果：
Hello, ‘world’!
Hello, ‘world’!
Hello, ‘world’!
I‘m fine!
Hello, ’world‘!

hbghlyj

1. \documentclass{article}
3. \catcode`'=13 % Make ' an active character
4. \def\lq{\char96\let'\rq}
5. \def\rq{\char39\let'\lq}
6. \let'\lq
7. \begin{document}
9. Hello, 'world'!
11. Hello, 'world'!
13. \end{document}

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Hello, ‘world’!
Hello, ‘world’!