Re: Plain TeX: Aligning to an earlier centered line's ends

On Wed, Jan  7, 2026 at 13:58 (-0800), Suresh Govindachar via texhax wrote:

> On 1/7/2026 6:17 AM, Suresh Govindachar wrote:
>> Hello,

>> A page has a centered line (via "\centerline{}"):  "Left end of a
>> centered line; its right end."

>> The line below that, "Aligned to L", needs to be left-aligned to "L"
>> of the centered line.

>> The line below that, "Aligned to period.", needs to be right-aligned
>> to "." of the centered line.

>> How exactly to achieve this (create a hbox to the size of the centered
>> line, center this hbox, insert the text inside this hbox with hss on
>> the right for left-alignment and hss on the left for right alignment)?

> \setbox0=\hbox{Left end of a centered line; its right end.}
> \centerline{\copy0}

> \vskip1in
> \hbox to \hsize{%
>   \hss
>   \hbox to \wd0{%
> Aligned to L\hss
>   }%
>   \hss
> }

> \vskip1.5in
> \hbox to \hsize{%
>   \hss
>   \hbox to \wd0{%
>     \hss Aligned to period.
>   }%
>   \hss
> }

Hi Suresh,

you may have already seen the nice \halign solution someone posted (sorry
to the poster, I deleted the message after reading it).

But if you don't want to use that for some reason, you can simplify your
solution above (which I think has a space after "Aligned to period." anyway)
by using \centerline{}.  Here is something like your solution, without the
\vskips.

\setbox0=\hbox{Left end of a centered line; its right end.}
\centerline{\copy0}
\centerline{\hbox to \wd0{Aligned to L\hss}}
\centerline{\hbox to \wd0{\hss Aligned to period.}}

Cheers.
                                Jim