match first columns in two files - perl

Question

I have two files of unequal sizes. First file has two columns and second has only one column. I want to match the column in second file to the first column in first file and if they match, print the whole line from the first file. Pretty simple but I am stuck. Here's what I did after opening and storing the contents of both the files in arrays
foreach(#q) #second file
{
$line=$_;
foreach(#gs) #first file
{
$line1=$_;
if ( $line1=~ /$line/ )
{
print $line1;
}
}
}
This doesnt give an output.

Answer 1

I suspect you might be getting tripped up by line endings for one or both of your files. Regardless, it's not necessary to slurp both your files, just the 2nd one. And a regex is most likely overkill, a simple equality check is sufficient, and more likely what you intend.
The following is probably what you intend:
use strict;
use warnings;
use autodie;
my $file1 = 'foo.txt';
my $file2 = 'bar.txt';
open my $fh2, '<', $file2;
my #keys = <$fh2>;
chomp(#keys);
open my $fh1, '<', $file1;
while (my $line = <$fh1>) {
my $fields = split ' ', $line;
if (grep {$fields[0] eq $_} #keys) {
print $line;
}
}

Answer 2

use strict;
use warnings;
my $file2 = 'foo.txt';
my $file1 = 'bar.txt';
my #line1;
open FF,$file2;
while(<FF>)
{
unshift(#line1,$_);
}
close(FF);
open FH,$file1;
while(<FH>)
{
my $se=$_;
chomp($se);
foreach my $data (#line1)
{
if($data=~m/^\s*$se\s*\t/is)
{
print $data."\n";
}
}
}
close(FH);
Try This....