Calling C-r with Prefix Argument

Calling C-r with Prefix Argument

[Christopher Dimech]

   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?

   Regards
   C*

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.)

Re: Calling C-r with Prefix Argument

[Daniel Martín]

Christopher Dimech <dimech@gmx.com> writes:
>
>    Tried to see the documentation for Prefix Argument but has not helped
>    me for the command C-r.
>

This is the part of the Emacs manual (under "7.10 Numeric Arguments")
that describes how a prefix argument changes the meaning of a command
like C-r:

   Some commands care whether there is an argument, but ignore its
value.  For example, the command ‘M-q’ (‘fill-paragraph’) fills text;
with an argument, it justifies the text as well.  (*Note Filling::, for
more information on ‘M-q’.)  For these commands, it is enough to specify
the argument with a single ‘C-u’.

Re: Calling C-r with Prefix Argument

[Christopher Dimech]

   I have read more now and with the initial help I got there. Many
   thanks.

   Sent: Wednesday, October 14, 2020 at 11:36 PM
   From: "Daniel Martín" <mardani29@yahoo.es>
   To: "Christopher Dimech" <dimech@gmx.com>
   Cc: "Help Gnu Emacs" <help-gnu-emacs@gnu.org>
   Subject: Re: Calling C-r with Prefix Argument
   Christopher Dimech <dimech@gmx.com> writes:
   >
   > Tried to see the documentation for Prefix Argument but has not helped
   > me for the command C-r.
   >
   This is the part of the Emacs manual (under "7.10 Numeric Arguments")
   that describes how a prefix argument changes the meaning of a command
   like C-r:
   Some commands care whether there is an argument, but ignore its
   value. For example, the command ‘M-q’ (‘fill-paragraph’) fills text;
   with an argument, it justifies the text as well. (*Note Filling::, for
   more information on ‘M-q’.) For these commands, it is enough to specify
   the argument with a single ‘C-u’.