How to use Emacs character classes in regex?

Question

The Emacs documentation has a section on character classes . According to the manual, [:digit:] must match any digit character. I tried using re-builder , but they never match, although [0-9] matches.

How to use character classes in an Emacs regex?

Answer 1

I get it. The documentation is actually explicit:

Here is a class table in which you can use alternate characters

So, [[:digit:]] is the right way to use character classes.