Greetings. I'm sure this is probably an FAQ, but I can't find it.

I have a script that basically does this:

printf "%-38s%s\n",left_column_info,right_column_info;

The problem is that when the left_column_info is too short, there's a big
gap.

I'd like to use what I think are called "leaders" ... where the output
would something like this: (monospace text ahead)

left_column_info . . . . . . . . . right_column_info
long_left_column_info . . . . . . right_column_info

Is there an easy way to do this, where there is
* at least one space after left_column_info
* the dots are aligned in columns
?

The only thing I can think of is
* get the length(left_column_info)
* add 1 space if the number is (let's say) even
* add " ." until the length is (in this case) 37

But I wonder if printf will do it for me.

Thanks.

--hymie! http://nasalinux.net/~hymie hymie@nasalinux.net

On 11/22/23 07:30, hymie! wrote:
> But I wonder if printf will do it for me.

It's been too long since I've done anything like this so I don't know.

I do think that printf had an option where you could specify the
character that was used to pad with. I don't know if that had to be a
singular character or if it could e a multi-character pattern. --
though I don't know what the alignment would be like.

One trick I would wonder about if you were printing to a terminal would
be to print the entire line with the dot pattern space and then over
print it with the left_column and a space. But that might not work for
your application.

Grant. . . .

hymie! <hymie@nasalinux.net> writes:

> I'd like to use what I think are called "leaders" ... where the output
> would something like this: (monospace text ahead)

> left_column_info . . . . . . . . . right_column_info
> long_left_column_info . . . . . . right_column_info

The code below ought to do it.
Maybe add some error checking for the proper arguments to print subroutine.

-- HASM

#! /usr/bin/perl

use Modern::Perl;
use List::Util qw(max);

sub dot_printf {
my $width = shift;
my $left_string = shift;
my $right_string = shift;

my $len_left = length($left_string);
my $len_dots = max(0, $width-$len_left);
printf ("%-*s %s %s\n", $len_left, $left_string, '.'x$len_dots, $right_string);
}

my $widht = 38;
dot_printf $widht, 'left string', 'right_string';
dot_printf $widht, 'larger string', 'right_string';

On 11/22/23 09:22, HASM wrote:
> printf ("%-*s %s %s\n", $len_left, $left_string, '.'x$len_dots, $right_string);

Wouldn't that end up with:

left_column_info...................right_column_info
long_left_column_info..............right_column_info

Or am I misunderstanding the '.'x$len_dots part?

Though I do wonder if you might be able to tweak that to be something
akin to:

'. 'x$len_dots/2

Type thing.

Grant. . . .

hymie! <hymie@nasalinux.net> writes:
> Greetings. I'm sure this is probably an FAQ, but I can't find it.
>
> I have a script that basically does this:
>
> printf "%-38s%s\n",left_column_info,right_column_info;
>
> The problem is that when the left_column_info is too short, there's a big
> gap.
>
> I'd like to use what I think are called "leaders" ... where the output
> would something like this: (monospace text ahead)
>
> left_column_info . . . . . . . . . right_column_info
> long_left_column_info . . . . . . right_column_info
>
> Is there an easy way to do this, where there is
> * at least one space after left_column_info
> * the dots are aligned in columns
> ?
>
> The only thing I can think of is
> * get the length(left_column_info)
> * add 1 space if the number is (let's say) even
> * add " ." until the length is (in this case) 37
>
> But I wonder if printf will do it for me.

I don't think printf will do this directly. You can certainly do it
with string manipulation, but I think that `format` might be the best
solution. `perldoc perlform` for details. (Disclaimer: I haven't
thought about Perl's format feature in years, so I'm not at all sure
that it's suitable.)

Other than that, initializing a string with ". . . . . ."... and then
overwriting parts of it may be the best solution.

--
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Will write code for food.
void Void(void) { Void(); } /* The recursive call of the void */

In our last episode, the evil Dr. Lacto had captured our hero,
Grant Taylor <gtaylor@tnetconsulting.net>, who said:
> On 11/22/23 09:22, HASM wrote:
>> Awesome program that I'm now playing with.
>> printf ("%-*s %s %s\n", $len_left, $left_string, '.'x$len_dots, $right_string);
>
> Wouldn't that end up with:
>
> left_column_info...................right_column_info
> long_left_column_info..............right_column_info

Yes it does.

> Though I do wonder if you might be able to tweak that to be something
> akin to:

I've got this:

use List::Util qw(max);

sub dot_printf {
my $width = shift;
my $left_string = shift;
my $right_string = shift;

my $len_left = length($left_string);
$len_left++ if ($len_left % 2);
my $len_dots = max(0, $width-$len_left);
printf ("%-*s %s%s\n", $len_left, $left_string, '. 'x ($len_dots/2),
$right_string);
}

And I think it does exactly what I want.

Thank you very much HASM

--hymie! http://nasalinux.net/~hymie hymie@nasalinux.net

On 11/22/23 11:41, hymie! wrote:
> And I think it does exactly what I want.

Cool.

My concern would be ending up with lines of output not having dots line
up, depending on the length of the left column. Even vs odd length type
thing.

If that does happen, you could probably add a space for the remainder
(modulus) of the length of the left column divided by two.

Grant. . . .

>>> printf ("%-*s %s %s\n", $len_left, $left_string, '.'x$len_dots,
>>> $right_string);
>> Wouldn't that end up with:
>> left_column_info...................right_column_info
>> long_left_column_info..............right_column_info

Not quite, I misread the initial requirement, but did bracket the dot
sequence with spaces, i,e., one would get

left column info ...................... right_column_info
long_left column info ................. right_column_info

> Thank you very much HASM

You're welcome.

I think I've only used printf's * field width once (and also $
positional ordering) more than 20 years ago on a C program, but your
post triggered my memory and I was almost certain Perl would have it.

-- HASM

HASM <hasm@example.invalid> writes:

>>>> printf ("%-*s %s %s\n", $len_left, $left_string, '.'x$len_dots,
>>>> $right_string);
>>> Wouldn't that end up with:
>>> left_column_info...................right_column_info
>>> long_left_column_info..............right_column_info
>
> Not quite, I misread the initial requirement, but did bracket the dot
> sequence with spaces, i,e., one would get
>
> left column info ...................... right_column_info
> long_left column info ................. right_column_info
>
>> Thank you very much HASM
>
> You're welcome.
>
> I think I've only used printf's * field width once (and also $
> positional ordering) more than 20 years ago on a C program, but your
> post triggered my memory and I was almost certain Perl would have it.

But why? printf("%-*s", length($s), $s) is just printf("%s", $s).

--
Ben.

hymie! <hymie@nasalinux.net> writes:
> Greetings. I'm sure this is probably an FAQ, but I can't find it.
>
> I have a script that basically does this:
>
> printf "%-38s%s\n",left_column_info,right_column_info;
>
> The problem is that when the left_column_info is too short, there's a big
> gap.
>
> I'd like to use what I think are called "leaders" ... where the output
> would something like this: (monospace text ahead)
>
> left_column_info . . . . . . . . . right_column_info
> long_left_column_info . . . . . . right_column_info

[...]

> The only thing I can think of is
> * get the length(left_column_info)
> * add 1 space if the number is (let's say) even
> * add " ." until the length is (in this case) 37
>
> But I wonder if printf will do it for me.

Why not just translate your algorithm into Perl?

-----
sub dot_print {
my ($w, $l, $r) = @_;

$l .= ' ' unless length($l) & 1;
$l .= ' .' while length($l) < $w;
print($l, ' ', $r, "\n");
}

dot_print(38, 'left_column_info', 'right_column_info');
dot_print(38, 'long_left_column_info', 'right_column_info');
-----

IMHO, doing anything more fancy just makes the code needlessly
complicated.

Rainer Weikusat <rweikusat@talktalk.net> writes:
> hymie! <hymie@nasalinux.net> writes:

[...]

>> The only thing I can think of is
>> * get the length(left_column_info)
>> * add 1 space if the number is (let's say) even
>> * add " ." until the length is (in this case) 37
>>
>> But I wonder if printf will do it for me.
>
> Why not just translate your algorithm into Perl?
>
> -----
> sub dot_print {
> my ($w, $l, $r) = @_;
>
> $l .= ' ' unless length($l) & 1;
> $l .= ' .' while length($l) < $w;
> print($l, ' ', $r, "\n");
> }
>
> dot_print(38, 'left_column_info', 'right_column_info');
> dot_print(38, 'long_left_column_info', 'right_column_info');
> -----

Slight correction: The lines produced by the code above are too long.

----
sub dot_print {
my ($w, $l, $r) = @_;

$l .= ' ' unless length($l) & 1;
$l .= ' .' while $w - length($l) > 1;
print($l, ' ', $r, "\n");
}