RE: Calling C-r with Prefix Argument

[Drew Adams]

>    Have been reading the output of describe-key for C-r (isearch-
> backward)
>    that does an incremental search backward.
>    It states that with a prefix argument, it does a regular expression
>    search instead.
> 
>    Tried to see the documentation for Prefix Argument but has not
> helped
>    me for the command C-r.
> 
>    How does a Prefix Argument work with C-r and what happens?

+1 for starting to read the documentation.

`C-u C-r' does a regexp incremental search backward.

(`C-M-r' does the same thing.)