emacs - Unexpected behavior in uppercase regexp using Emacs

Question

I am trying to have an inbetween step for deleting words backwards, which should stop at a capital letter (in the case of camelCase).

For this I thought to use the following to obtain the position of the first capital letter backwards:

(search-backward-regexp "[:upper:]")

If you'd run this when point is after that last parenthesis, it will go here:

(search-backward-regexp "[:upper | :]"), that is, after the r.

How so?

Answer 1

（向后搜索正则表达式“[[:upper:]]”）

[:upper:]还不是“上部”调用，而只是一个匹配单个字符的字符类，该字符必须是“：”或“u”或“p”或“e”或“r”之一。只有第二个“ []”使它搜索类。

Answer 2

安德烈亚斯的回答是正确的。但是，根据您要实现的目标，我建议您看一下subword-mode（它与 emacs 捆绑在一起，至少对于现代 emacsen 而言）

Answer 3

我现在意识到它与变量有关case-fold-search。

当设置为 时t，它将忽略搜索中的大小写。