string concatenation in perl

[threadhead]

hi!!

i want to check if a given length of a string matches 4 without remainder.
if 1 or 3 remain i want to add a leading zero to the string.


if($size % 4 == 1 || 3)
{
"0" . "$binhex";
print "$binhex";
}
elsif($size % 4 == 2)
{
"00" . "$binhex";
}


that doesnt work because "0" doesnt exist in perl i think....
adding two zeros doesnt work either.
the interpreter tells me something like
useless use of concatenation.
uhm that hurts :confused:
how could i get this working?

thanks

[karthik]

You do not need the double quotes ( " ) surrounding $binhex, try "0" . $binhex , it shoud do the trick

[rid3r]

try this:
if(($size % 4) == ( 1 || 3 )) #possible logical error
{
$binhex .= "0";
print "$binhex";
}
elsif(($size % 4) == 2)
{
$binhex .= "00";
print "$binhex";
}

[stumbles]

Originally posted by threadhead
hi!!

i want to check if a given length of a string matches 4 without remainder.
if 1 or 3 remain i want to add a leading zero to the string.


if($size % 4 == 1 || 3)
{
"0" . "$binhex";
print "$binhex";
}
elsif($size % 4 == 2)
{
"00" . "$binhex";
}


that doesnt work because "0" doesnt exist in perl i think....
adding two zeros doesnt work either.
the interpreter tells me something like
useless use of concatenation.
uhm that hurts :confused:
how could i get this working?

thanks


Whadya know, I just got my Learning Perl book today. So feel free to ignore anything I say.

Your right, "0" doesn't exist in Perl. However what about using the "undef" value? If you create a variable say, $string and not define it, it starts out empty. Maybe you could work with that?

[scinerd]

this works you can change the size to test it.

#!/usr/bin/perl

use strict;
use warnings;

my $size = 6;
my $binhex = "string";
my $rd = $size%4;

if($rd == (1 || 3))
{
$binhex = "0$binhex";
print "$binhex \n";
}
elsif($rd == 2)
{
$binhex = "00$binhex";
print "$binhex \n";
}

[rid3r]

or
$binhex = "0". "$binhex" ; # if the "0" goes in front

[threadhead]

thanks for all your replies!
scinerd i tried your solution, it works. thanks ;)


rid3r doesnt that append the zeros to the end of the string?

cya