Re: Why does "\024" mean `C-t'? (in bindkey example in man page)

Lovely, thank you very much Axel and Pieter!

Why does pressing ctrl-1 make 1, and pressing ctrl-3 make ^[ ?  Pressing
ctrl-8 makes nothing, like Pieter said (you can't shift 042 down by 64).

Axel's script was very helpful! I added display of the binary value which
helped me to understand the relationship between character, lower-case
version, and control-version:

    perl -E 'while (my $l=<>){ chomp($l); say join(" ", map { my
$c=ord($_); sprintf("x%02X=o%03o=d%i", $c,$c,$c) } split(//,$l)) }'

So it seems like ^A is the "base" form, and upper-case and lower-case
versions are modifications of that base.

  ^A
  b00000001 = x01 = o001 = d1

  A
  b01000001 = x41 = o101 = d65

  a
  b01100001 = x61 = o141 = d97

It's funny, because I think of Control as being some extra that I add, but
really it's the basic form.  Still trying to wrap my mind around that...  I
read the first version of the standard (1963), which I found through
https://en.wikipedia.org/wiki/ASCII#History but there is no mention there
of using the alphabet to represent control characters.  I have to go off to
work now but I plan to study subsequent versions of the standard to
understand where that came in.

Thanks!!

Best,
Aleksey

On Sat, Aug 13, 2016 at 11:37 PM, Pieter Luteijn <luteijn-qWit8jRvyhVmR6Xm/[email protected]> wrote:

> Hi,
>
> In short, pressing ctrl+{other key} just sends a code that's 64 (dec)
> lower than then {other key} by itself. So ctrl-@ sends '0' (NUL), ctrl-C
> sends '3', ctrl-T '20'. To make it easy, no difference is made between
> upper/lowercase. Look at an ASCII table, as this method is/was meant to
> send codes from 0-31 (with 32 having its own key, spacebar), and you'll see
> why some non-letter {other keys} like '[' or ']' work, but others like e.g.
> '*' (usually) don't.
>
> Regards,
> Pieter
>
> Sent from a mobile, sorry for any typoes...
>
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