conditional string formatting

docdurdee has asked for the wisdom of the Perl Monks concerning the following question:

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Re: conditional string formatting by AnomalousMonk (Archbishop) on Jun 08, 2015 at 18:08 UTC
I'm not sure this is in any sense "simpler" (it certainly burns a lot more computrons than just checking the length and selecting a format string conditionally), but: `c:\@Work\Perl\monks>perl -wMstrict -le "my @names = qw(A AB ABC ABCD); ;; for my $name (@names) { my $s = sprintf '%4s', sprintf '%-3s', $name; print qq{'$s'}; } " ' A ' ' AB ' ' ABC' 'ABCD'` [download] See sprintf for format specifiers. Give a man a fish: `<%-(-(-(-<`	[reply] [d/l] [select]
Re^2: conditional string formatting by Discipulus (Canon) on Jun 08, 2015 at 18:40 UTC
Wow `the double sprintf maneuver` Perl is limited only by our fantasy.. ++AnomalousMonk There are no rules, there are no thumbs.. Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.	[reply] [d/l] [select]
Re^3: conditional string formatting by karlgoethebier (Abbot) on Jun 08, 2015 at 21:46 UTC
"double sprintf maneuver " Or perhaps The anomalous double sprintf maneuver? Sounds a bit like a bizarre chess combination. Regards, Karl «The Crux of the Biscuit is the Apostrophe»	[reply]
Re^3: conditional string formatting by AnomalousMonk (Archbishop) on Jun 08, 2015 at 20:44 UTC
It would have been nicer if I could have figured out a way to use a single `(s)printf`, but I couldn't. :-\ Give a man a fish: `<%-(-(-(-<`	[reply] [d/l] [select]
Re: conditional string formatting by choroba (Cardinal) on Jun 08, 2015 at 17:24 UTC
There is no 'center' option for printf. You have to check the length: `printf +(3 < length $in ? q() : ' ') . '%-3s', $in` [download] Or, more funny (and shorter): `printf ' ' x (4 > length $in) . '%-3s', $in` [download] لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l] [select]
Re^2: conditional string formatting by docdurdee (Scribe) on Jun 08, 2015 at 17:51 UTC
Thanks!	[reply]
Re: conditional string formatting by QM (Parson) on Jun 09, 2015 at 08:42 UTC
Simple and maintainable: `my %formats = ( 1 => ' %s ', 2 => ' %s ', 3 => ' %s', 4 => '%s', ); for my $x ("a", "bb", "ccc", "dddd") { printf $formats{length($x)}, $x; print "\n"; } ###################### a bb ccc dddd` [download] -QM -- Quantum Mechanics: The dreams stuff is made of	[reply] [d/l]
Re^2: conditional string formatting by AnomalousMonk (Archbishop) on Jun 10, 2015 at 00:34 UTC
++Very nice, and very easily extended to handle a default case! `c:\@Work\Perl\monks>perl -wMstrict -le "my %formats = ( 1 => ' %s ', 2 => ' %s ', 3 => ' %s', 4 => '%s', +); ;; for my $x ('a', 'bc', 'def', 'ghij', 'klmno') { printf qq{'@{[ $formats{length($x)} // '%4.4s' ]}' \n}, $x; } " ' a ' ' bc ' ' def' 'ghij' 'klmn'` [download] Give a man a fish: `<%-(-(-(-<`	[reply] [d/l] [select]
Re^3: conditional string formatting by QM (Parson) on Jun 10, 2015 at 08:39 UTC
...easily extended to handle a default case! Yes, I forgot to handle that. The defined-or touch is nice. While the `@{[]}` wrapper does the job, is it completely necessary? (Perhaps I have missed something in my uncaffeinated state?) Other than a quick crutch for interpolating inside `qq{}` while adding single quotes and appending a newline? -QM -- Quantum Mechanics: The dreams stuff is made of	[reply] [d/l] [select]
Re^4: conditional string formatting by AnomalousMonk (Archbishop) on Jun 10, 2015 at 14:00 UTC
Re: conditional string formatting by AnomalousMonk (Archbishop) on Jun 09, 2015 at 00:44 UTC
Actually, I think I like this one better than either choroba's or mine above: `c:\@Work\Perl\monks>perl -wMstrict -le "my @names = qw(A AB ABC ABCD ABCDE); ;; for my $name (@names) { printf qq{%8s -> }, qq{'$name'}; my $s = sprintf length($name) > 3 ? '%s' : ' %-3s', $name ; print qq{'$s'}; } " 'A' -> ' A ' 'AB' -> ' AB ' 'ABC' -> ' ABC' 'ABCD' -> 'ABCD' 'ABCDE' -> 'ABCDE'` [download] Make the first `'%s'` into `'%4.4s'` to limit the field to the first four characters only. Give a man a fish: `<%-(-(-(-<`	[reply] [d/l] [select]
Re: conditional string formatting by Tux (Canon) on Jun 08, 2015 at 16:36 UTC
`printf "%4.4s", $var." ";` Enjoy, Have FUN! H.Merijn	[reply] [d/l]
Re: conditional string formatting by GotToBTru (Prior) on Jun 08, 2015 at 16:42 UTC
Your strings are all 8 characters, not 4 ...? Clearly I'm missing something. Dum Spiro Spero	[reply]
Re^2: conditional string formatting by docdurdee (Scribe) on Jun 08, 2015 at 16:48 UTC
my apologies, I edited the initial post (which was pretty unclear the first time).	[reply]
Re^3: conditional string formatting by ww (Archbishop) on Jun 08, 2015 at 20:01 UTC
Please do NOT (EVER!) edit a previously-created question or reply without plainly marking what's new with a note about the fact of your editing and <strike>...</strike> tags around deletions: Added: "new text... and changed value of `my $var` at Ln 42, from 6 to 7 Note that you CAN NOT use markup tags inside code tag pairs but you can within most other markup... so, please, be vigilant about using strikeout tags around that which you're disavowing or deleting. Strike tag pairs render this way: ~~that which you're removing, changing, editing, emending, etc.~~ In this case, your edit removed the context for GotToBTru's reply. Yes, you provided clarification, but it makes a thread easier to read and understand if the edit info is with the original, and better yet, if you time-stamp your update note, so a careful reader can see if a reply pre-dates your change. For more, see Markup in the Monastery. EDITED: fixed markup errors that I missed on preview. Spirit of the Monastery	[reply] [d/l]
Re: conditional string formatting by superfrink (Curate) on Jun 10, 2015 at 05:56 UTC
You might find something in perlform. The following is close but puts the extra whitespace on the left instead of the right in the case of a length of one. Update: In this code `format` is not print the trailing `\s` characters. Sample output updated to show the whitespace is missing. `#! /usr/bin/perl -w use strict; for my $val (qw/a ab abc abcd/) { format = @\|\|\|\| $val . write \*STDOUT; }` [download] Output: `$ ./centre-via-format.pl a ab abc abcd $ ./centre-via-format.pl \| od -ch 0000000 a \n a b \n a b c \n a b c 2020 0a61 6120 0a62 6120 6362 610a 6362 0000020 d \n 0a64 0000022` [download]	[reply] [d/l] [select]