Number or string?

From: Aiguo Li (liai_at_mail.nih.gov)
Date: 02/22/05 

To: "'Graeme St. Clair'" <Graeme.St.Clair@hds.com>, beginners@perl.org
Date: Tue, 22 Feb 2005 10:17:18 -0500

Hi, all.

I have the following data from a file.
__data from file IN__
SNP_A-1512608 23 148840899 0.828109 0.823391
11128
SNP_A-1512550 23 148841154 1.717397 1.750476
11129
SNP_A-1518843 23 149078514 0.832285 0.99744 11130
SNP_A-1507809 23 149080794 1.463225 1.463085
11131
SNP_A-1519263 23 149309465 0.990172 1.124282
11132
SNP_A-1512795 23 149514662 1.37836 1.51924 11133
SNP_A-1518711 23 149890944 1.541307 1.920374
11134
SNP_A-1517959 23 150083331 0.535966 0.942863
11135

While I trying to get a difference between column 4 and column5, I got the
following error message:
"Argument "STD" isn't numeric in subtraction (-) at cpdiffer.pl line 19,
<IN> lin
e 1.
Argument "gli3ak" isn't numeric in subtraction (-) at cpdiffer.pl line 19,
<IN>
line 1."

MY QUESTIONS IS: why perl treat the numeric value in column 4 as string and
how to convert it?

Thanks,

AG Lee
The code is as below:

#!/bin/perl -w

#use strict;
use warnings;

my $differ;

open (IN, "C:/perl/work/data/cpdata.txt") or die ("Can not open cpdata.txt
file! \n");
open (OUT, ">C:/perl/work/data/cpout.txt") or die ("Can not open cpout.txt
file! \n");
while(my $line = <IN>)
{
chomp $line;

my ($snp, $chro, $location, $gli3ak, $std, $rest) = split(/\t/, $line);
#print $line;
#print "$snp, $chro, $location, $gli3ak, $std, $rest\n";

$differ = $gli3ak-$std;

if(($differ >= 2) || ($differ <= -1.5))
        {
        
        print OUT "$snp\t$chro\t$location\t$gli3ak\t$std\t$rest\n";
        }
        
}

Relevant Pages