Perl Regex Problem! - regex

Question

I am reading a string from a file:
2343,0,1,0 ... 500 times ...3
Above is an example of $_ when it is read from a file. It is any number, followed by 500 comma separated 0's/1's then the number 3.
while(<FILE>){
my $string = $_;
chomp($string);
my $a = chop($string);
my $found;
if($string=~m/^[0-9]*\,((0,|1,){$i})/){
$found = $&.$a;
print OTH $found,"\n";
}
}
I am using chop to get the number 3 from the end of the string. Then matching the first number followed by $i occurences of 0, or 1. The problem I'm having is that chop is not working on the string for some reason. In the if statement when I try to concat the match and the chopped number all I get returned is the contents of $&.
I have also tried using my $a = substr $a,-1,1; to get the number 3 and this also hasn't worked.
The thing that's odd is that this code works in Eclipse on Windows, and when I put it onto a Linux server it won't work. Can anyone spot the silly mistake I'm making?

Answer 1

As a rule, I tend always to allow for unseen whitespace in my data. I find that it makes my code more robust expecting that somebody didn't see an extra space at the end of a line or string (as in writing to a log). So I think this would solve your problem:
my ( $a ) = $string =~ /(\S)\s*$/;
Of course, since you know you are looking for a number, it's better to be more precise:
my ( $a ) = $string =~ /(\d+)\s*$/;

Answer 2

Take care of the end of line char… I can not test here but I assume you just chop a newline. Try first to trim your string then chop it. See for example http://www.somacon.com/p114.php

Answer 3

Instead of trying to do it that way, why not use a regexp to pull out everything you need in one go?
my $x = "4123,0,1,0,1,4";
$x =~ /^[0-9]+,((?:0,|1,){4})([0-9]+)/;
print "$1\n$2\n";
Produces:
0,1,0,1,
4
Which is pretty much what you're looking for. Both sets of needed answers are in the match variables.
Note that I included ?: in the front of the 0,1, matching so that it didn't end up in the output match variables.

Answer 4

I'm really not sure what you are trying to achieve here but I've tried the code on Win32 and Solaris and it works. Are you sure $i is the correct number? Might be easier to use * or ?
use strict;
use warnings;
while(<DATA>){
my $string = $_;
chomp($string);
my $a = chop($string);
print "$string\n";
my $found;
if($string=~m/^[0-9]*\,((0,|1,)*)/){
$found = $&.$a;
print $found,"\n";
}
}
__DATA__
2343,0,1,0,0,1,1,0,0,0,1,1,0,0,0,1,1,0,0,0,1,1,0,0,0,1,1,0,0,0,1,1,0,0,0,1,1,0,0,0,1,1,0,3

Answer 5

I don't see much reason to use a regex in this case, just use split.
use strict;
use warnings;
use autodie; # open will now die on failure
my %data;
{
# limit the scope of $fh
open my $fh, '<', 'test.data';
while(<$fh>){
chomp;
s(\s+){}g; # remove all spaces
my($number,#bin) = split ',', $_;
# uncomment if you want to throw away the 3
# pop #bin if $bin[-1] == 3;
$data{$number} = \#bin;
}
close $fh;
}
If all you want is the 3
while(<$fh>){
# the .* forces it to look for the last set of numbers
my($last_number) = /.*([0-9]+)/;
}