Grepping for a value in a hash of filenames and printing the matches

iphone has asked for the wisdom of the Perl Monks concerning the following question:

I am getting the following warning while running my code

Use of uninitialized value in pattern match (m//) at orphan_plf.pl line 37

and line 37 is $Hash_filematches{$filename}= grep( /\/\Q$file_name\E#/i, $Hash_filenames{$plf} ); The objective of my program

1.Get all the filenames with .plf extension from a directory

2.Store the filename as key and the corresponding lines of it as values in a hash

3.For every filename in the hash saved in step 2 grep for a filename in the corresponding lines and save the filename and the corresponding match in another hash and them print the hash

Please help

#!/usr/bin/perl -w  
use strict;   
use warnings;   
my %Hash_filenames=(); 
my %Hash_filematches=(); 
my $plf; 
my $start_dir; 
my $start_dir = \\server1\tools ; 
 
my $file_name = "load.c"; 
 
opendir(DIR, "$start_dir"); 
my @plf_files = grep(/\.plf$/,readdir(DIR)); 
print "PLF FILES\n"; 
print "@plf_files\n"; 

foreach my $plf (@plf_files) { 
chomp($plf); 
open my $match, '<',"$start_dir\\$plf" or die "could not open '$plf' $
+!"; 
my @file_lines = <$match>; 
#Save the filename as key and the lines in the file as value in a hash
+ 
$Hash_filenames{$plf}=@file_lines; 
} 
closedir(DIR); 
    if ($file_name)  {  
 
foreach my$filename(keys %Hash_filenames) { 

#for every  key(filename) in the above hash namely #$Hash_filenames  
#grep for  $file_name  in the  
#corresponding values (lines in the file)of the file  
#and save the match  as value and key as filename  
#in another hash 
$Hash_filematches{$filename}=  grep( /\/\Q$file_name\E#/i, $Hash_filen
+ames{$plf} );     
} 
}  
{  
    local $, = "\n";  
    print "PRINTING MATCHED HASHES"; 
foreach my $key ( keys %Hash_filenames ) { 
        my $value = $Hash_filematches{$key}; 
        print "$key => $value\n"; 
    } 
}
[download]

Comment on Grepping for a value in a hash of filenames and printing the matches Download Code

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Re: Grepping for a value in a hash of filenames and printing the matches by jwkrahn (Abbot) on Oct 27, 2010 at 06:35 UTC
Change: `$Hash_filenames{$plf}=@file_lines;` [download] To: `$Hash_filenames{ $plf } = \@file_lines;` [download] And change: `$Hash_filematches{$filename}= grep( /\/\Q$file_name\E#/i, $Hash_filen +ames{$plf} );` [download] To: `@{ $Hash_filematches{ $filename } } = grep /\Q/$file_name\E#/i, @{ $Ha +sh_filenames{ $plf } };` [download]	[reply] [d/l] [select]
Re^2: Grepping for a value in a hash of filenames and printing the matches by iphone (Beadle) on Oct 28, 2010 at 00:32 UTC
Thanks for the reply. I am getting "Use of uninitialized value in hash element at orphan_plf.pl line 40" and line 40 is @{ $Hash_filematches{ $filename } } = grep( /\/\Q$file_name\E#/i, @{ $Hash_filenames{ $plf } }); and the output is PRINTING MATCHED HASHES apps.plf => ARRAY(0x1981c80) modem.plf => ARRAY(0x1981ca4) ........... 1.I am confused on why apps.plf is showing beacause the file we are grepping is not in this PLF. 2.the output is printing the reference values,how do I fix this?Please help	[reply]
Re: Grepping for a value in a hash of filenames and printing the matches by ikegami (Patriarch) on Oct 27, 2010 at 07:20 UTC
`$Hash_filenames{$plf}=@file_lines;` An array evaluated in scalar context returns the number of elements it contains. A hash element is a scalar. It cannot contain an array. It can contain a reference to an array. Fix: `my @file_lines = <$match>; $Hash_filenames{$plf} = \@file_lines;` [download] or `$Hash_filenames{$plf} = [ <$match> ];` [download] `$Hash_filematches{$filename}= grep( /\/\Q$file_name\E#/i, $Hash_filenames{$plf} );` `$Hash_filenames{$plf}` is a scalar, so your grep is going to return at most one item. You call `grep` in scalar context, so it returns the number of matching items rather than the items themselves. You never assigned a value to `$plf`. Fix for the first two: `$Hash_filematches{$filename} = [ grep( /\/\Q$file_name\E#/i, @{ $Hash_filenames{$plf} } ) ];` [download] Sorry, I don't have time to understand what you are trying to do in order to propose a solution for the third item. But maybe knowing what the problem is will help you.	[reply] [d/l] [select]
Re: Grepping for a value in a hash of filenames and printing the matches by suhailck (Friar) on Oct 27, 2010 at 05:52 UTC
Are you trying to achieve something which can be easily done using grep in nix systems `grep -R 'pattern' .plf`	[reply] [d/l]
Re: Grepping for a value in a hash of filenames and printing the matches by umasuresh (Hermit) on Oct 27, 2010 at 12:52 UTC
`use Data::Dumper` to see what is in your Hash or other complex Data Structure.	[reply] [d/l]