边读 Emacs Lisp Intro 边做题（五）

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• [边读`Emacs Lisp Intro`边做题（五）](#边读Emacs Lisp Intro边做题（五）)

边读Emacs Lisp Intro边做题（五）

打开emacs，按C-h i打开Info页，找到Emacs Lisp Intro。

1. 这里的\\b\\([^@ \n\t]+\\)[ \n\t]+\\1\\b抄自题目描述中提供的链接，即Appendix A The 'the-the' Function。
2. 该链接中也提供了答案，但是我没有照抄，下面是我自己写的：
3. (save-excursion (goto-char (point-max)))是指将光标移至buffer最后，返回它的位置，为re-search-forward提供搜索界限。

(defun exercise-12.6.2 ()
  "exercise 12.6.2

Write a function to search for duplicated words, such as "the
the". *Note Syntax of Regular Expressions: (emacs)Regexps, for
information on how to write a regexp (a regular expression) to
match a string that is composed of two identical halves.  You can
devise several regexps; some are better than others.  The
function I use is described in an appendix, along with several
regexps. *Note 'the-the' Duplicated Words Function: the-the."
  (interactive)
  (let ((pattern "\\b\\([^@ \n\t]+\\)[ \n\t]+\\1\\b"))
    (re-search-forward pattern (save-excursion (goto-char (point-max))) nil 1)))