IMO, the most convenient way to handle fixed-width records is with pack to write and unpack to read. Pack is usable either with arrays or lists of variables.

my @data = qr/foo bar bazaquuxinator/;
my $format = q(A3 A10 A3 A35);
my $line = pack $format, @data;
print $line, $/;
my $line = pack $format, @data[0,1], 'quux', $data[2];
print $line, $/;
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That prints,

foobar       baz                                   
foobar       quubazaquuxinator                     
$

There is no need to init variables with padded strings. Consider:

my $zip_1 = '';
#...
printf ">%12.12s<\n", $zip;
printf ">%12.12s<\n", '123456789012';
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Prints:

>            <
>123456789012<
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To manage multiple successive entries that ought be the same length:

my @lines;

push @lines, 'Address line 1';
push @lines, ''; # Second line of address skipped
push @lines, 'no zip stupid form';
push @lines, 'My beloved country';
push @lines, 'The %35.35s syntax will truncate this is a long line.';

printf "%-35.35s\n", $_ for @lines;
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Prints:

Address line 1                     
                                   
no zip stupid form                 
My beloved country                 
The %35.35s syntax will truncate th
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But why fixed length records rather than CSV, XML or using a database?

First off, fixed length is the requirement of the client, I have no say in that. yay me.
I don't have muliple successive entries that need to be the same length. The fields are of various lengths scattered throughout the file layout. My badly-formed original question was looking to see if I could

push @lines35char, $value1;
push @lines35char, $value13;
push @lines35char, $value 22;
sprintf "%-35.35s", $_ for @lines35char;
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and then have those padded values show up when I build the line, like so:
$fl_line = join '', $filetype, $batch, $serial, $sys_time, $value1, $t_lastname, $t_firstname, $t_mi, $t_mi, $ssn, $ssn_cor, $dob, $t_address, $t_city, $t_state, $t_zip, $value13, $t_country, $code_1, $date_1, $type_1, $priority_1, $addressee_1, $institution_1,$value22;
or do I have to reference them as they are related to the array?
Thanks!
I learn more and more about less and less until eventually I know everything about nothing.

You could toss the various values into arrays. Something tht may help is:

use warnings;
use strict;

my @fields;

my $fieldValue = 'Grand'; # Given name field contents
push @fields, [$fieldValue, 10]; # 20 character wide field

$fieldValue = 'Father'; # Sir name
push @fields, [$fieldValue, 10]; # 25 character wide field
push @fields, ['007 Bond Street', 15];
push @fields, ['Wibble Wobble', 15];
push @fields, ['', 15];
push @fields, ['Erewhon', 15];
#...

my $record = join '', map {sprintf "%-*.*s", $_->[1], $_->[1], $_->[0]
+} @fields;

print $record;
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Prints:

Grand     Father    007 Bond StreetWibble Wobble                 Erewh
+on
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which ties the field size to the field contents at the point where the contents are added to the field list then uses the field size to control field width in a sprintf later on.

---

DWIM is Perl's answer to Gödel

Why would you go to the trouble of pre-padding them? I'm pretty sure you'd be better off performance-wise to just call sprintf once (if that's any sort of concern).

Assuming an example where odd fields are 5 chars long and evens 15:

my $var1, $var2, $var3, $var4, $var5; #hopefully you'll be using some 
+meaningful names instead

my $format = "%5s%15s%5s%15s%5s\n"; #you could embed spaces in the for
+mat specifier too if needed

#check/process inputs here 
#....

$outputline = sprintf $format, $var1, $var2, $var3, $var4, $var5;
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See the sprintf documentation (pg 797 of Programming Perl 3rd e) for other formats if you need to deal with formatting numerics.

You can break the format statement up or use repeat specifications too so you don't lose count:

my $format = "%5s%5s%5s%5s%5s"."%5s%5s%5s%5s%5s"."%5s%5s%5s%5s%5s".
             "%5s%5s%5s%5s%5s"."%5s%5s%5s%5s%5s"."%5s%5s%5s%5s%5s".
             "%5s%5s%5s%5s%5s"."%5s%5s%5s%5s%5s";

my $otherformat" = "%5s"x40;
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(Though the former is likely to be unwieldy when the client changes the content three times a day)

I think you are correct in pursuing sprintf as one good way to skin this cat. But I must admit, I personally prefer working with delimited records to fixed-length records any day of the week. Are you sure you can't do this with a delimiter, rather than fixed-length?

If you decide you must use a fixed-length strategy, you might try declaring a hash with attribute names and expected string length (or other formatting instructions). Then you could pass each form input to a standard write_me() routine that would look up the appropriate formatting instruction and write it out to your file (or whatever).

I'm sure there are lots of TIMTOWTDI variations. :)

The fixed-length issue is a requirement from the client. They're defining the file format, i just have to deal with it. I too prefer delimited. I personally love |.
Thanks for the suggestions.


I learn more and more about less and less until eventually I know everything about nothing.

Also be sure to consider whether a field's data should be truncated if it exceeds the maximum width. The thread I referenced has snippets of both forms: pad-or-truncate, and just pad.

# format for fixed-length line:
    my $filebegin_format = "%-1.1s%-8.8s%-6.6s%-17.17s%-25.25s%-16.16s
+%-1.1s%-9.9s%-9.9s%-8.8s%-35.35s%-25.25s%-2.2s%-12.12s%-3.3s"; #file 
+layout for characters 1-177
    my $request_format = "%-4.4s%-4.4s%-1.1s%-1.1s%-35.35s%-35.35s%-35
+.35s%-25.25s%-2.2s%-12.12s%-3.3s%-4.4s"; #file layout for requests 1-
+8 
    my $request9_format = "%-6.6s%-4.4s%-4.4s%-1.1s%-1.1s%-1.1s%-35.35
+s%-35.35s%-35.35s%-25.25s%-2.2s%-12.12s%-3.3s%-4.4s"; #file layout fo
+r request 9
    my $fileend_format = "%-5.5s%-1.1s%-16.16s%-4.4s%-25.25s%-16.16s%-
+9.9s%-1.1s%-40.40s%-14.14s%-2.2s%-9.9s%-3.3s%-3.3s%-10.10s%-40.40s%-2
+2.22s%-1.1s"; #file layout for characters 1630-1850
    my $format = $filebegin_format . $request_format . $request_format
+ . $request_format . $request_format . $request_format . $request_for
+mat . $request_format . $request_format . $request9_format . $fileend
+_format;
    
# build fixed-length line:
    $fl_line = sprintf $format, $filetype, $batch, $serial, $sys_time,
+ $t_lastname, $t_firstname, $t_mi, $t_mi, $ssn, $ssn_cor, $dob, $t_ad
+dress, $t_city, $t_state, $t_zip, $t_country, $code_1, $date_1, $type
+_1, $priority_1, $addressee_1, $institution_1, $address_1, $city_1, $
+state_1, $zip_1, $country_1, $filler, $code_2, $date_2, $type_2, $pri
+ority_2, $addressee_2, $institution_2, $address_2, $city_2, $state_2,
+ $zip_2, $country_2, $filler, $code_3, $date_3, $type_3, $priority_3,
+ $addressee_3, $institution_3, $address_3, $city_3, $state_3, $zip_3,
+ $country_3, $filler, $code_4, $date_4, $type_4, $priority_4, $addres
+see_4, $institution_4, $address_4, $city_4, $state_4, $zip_4, $countr
+y_4, $filler, $code_5, $date_5, $type_5, $priority_5, $addressee_5, $
+institution_5, $address_5, $city_5, $state_5, $zip_5, $country_5, $fi
+ller, $code_6, $date_6, $type_6, $priority_6, $addressee_6, $institut
+ion_6, $address_6, $city_6, $state_6, $zip_6, $country_6, $filler, $c
+ode_7, $date_7, $type_7, $priority_7, $addressee_7, $institution_7, $
+address_7, $city_7, $state_7, $zip_7, $country_7, $filler, $code_8, $
+date_8, $type_8, $priority_8, $addressee_8, $institution_8, $address_
+8, $city_8, $state_8, $zip_8, $country_8, $filler, $code_9, $date_9, 
+$type_9, $exception_9, $priority_9, $addressee_9, $institution_9, $ad
+dress_9, $city_9, $state_9, $zip_9, $country_9, $filler, $bill_total,
+ $cc_type, $cc_number, $cc_exp, $cc_name, $cur_lastname, $cur_firstna
+me, $cur_mi, $cur_address, $cur_city, $cur_state, $cur_zip9, $cur_pco
+de, $cur_country, $phone, $email, $filler, $reject;
    
    my $asr_line = uc($fl_line); #make the line uppercase
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