Re^3: Filtering Output from two files

[LanX]

You have at least one bug of forgetting sigil $ in line once, but yes this was the basic idea.

And dumping inside the loop is costly.

Furthrmore you might want to use <code> tags next time. :)

Minor nitpick: when setting value 1, you don't need exists anymore. :)

[vighneshmufc]

It is me who posted anonymously since we aren't allowed to log in at the university.
I didn't get where I missed "sigil $ in line once".
Furthermore, i am getting errors such as Use of uninitialized value in line 34 at variables $row and $fields at the penultimate line.
So when i place the  print $row if exists $hash{$fields[0]}; after the loop it gives an error "Perl requires explicit package name"
i am really a novice at this if you could guide me in this I would learn more.

[LanX]

> It is me who posted anonymously 

I'm glad you are making progress. :)

> I didn't get where I missed "sigil $ in line once". 

$hash{line}=1;  
# should be
$hash{$line}=1;

> Use of uninitialized value in line 34 

You probably parse empty lines resulting in undefined variables.

Skip them with next , compare Re: Filtering Output from two files

>  after the loop 

The print belongs inside the loop.

please use code tags and indentation in your next post.

[Anonymous Monk]

use strict; <br>
use warnings; <br>
use Data::Dumper; <br>

my $file1 = 'file1';<br>
my $file2 = 'file2'; <br>
#reading file1 into a hash<br>

my %hash;<br>

open (my $fh,'<',$file2) or die $!;<br>
while(my $line=<$fh>)<br>
{<br>
chomp $line;<br>
$hash{$line}=1;<br>

print Dumper %hash;<br>
}<br>
close $fh;<br>


#reading file2 line by line
<br>
open (my ($fh2),'<',$file1) or die $!;
<br>
while (my ($row) = <$fh2>) {<br>
  chomp $row;<br>
# next if $row =~ /^\s*$/;<br>
my (@fields) = split(/\|/, $row);<br>
print $row if exists $hash{$fields[0]};<br>
}<br>

close $fh2;<br>


I aint getting any O/P plus when i print Dumper %hash i get loads of $VAR
What am i doing wrong?

[roboticus]

Anonymous Monk:

What am i doing wrong?

1. When you're calling Dumper, you're giving it a hash as an argument. The hash expands to a list of key/value pairs, and each of those is being printed as a separate value. You want to pass it a reference to the hash, like:
   

   print Dumper(\%hash);
   

2. You should put your print statement after the end of your loop. As it is now, you're printing the hash after adding each line to it, so you're getting far more output than you really want. (Unless, of course, you're really wanting to see the hash after each line is added.)
3. If you're on a windows box, then chomp may not be removing all the whitespace at the end of the line. I generally avoid chomp and use something like:
   

    $line =~ s/\s+$//; # trim whitespace
   

If you're still not getting output, you may want to add:

print "<$fields[0]>\n";

in the loop where you're searching for, so you can see what key is being looked for, and compare that against the keys displayed by Dumper previously.

...roboticus

When your only tool is a hammer, all problems look like your thumb.

[Anonymous Monk]

damn just realised i messed up the print statement inside the loop as u said i had to put it out of the loop. sorry i am very new to programming hence the mistakes