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

Hello Everyone,
Please see following code:

 sub Clear{
    my $item=$_[0];
    $item=~s/^\s+//;
    $item=~s/\s+$//;
    return $item;
}

sub Txn_Extract{
    my $name_of_file=$_[0];
    my $hash_ref=$_[1];
        $hash_ref=Clear($hash_ref);       #Here something goes wrong. 
+When I remove this line %DATA_HASH gets populated properly. Need to k
+now what happens when I clear the $hash_ref variable with above sub C
+lear.
    my @row;
.
..
.
.
}
sub Main {
       Txn_Extract (file.txt,\%DATA_HASH);
       print Dumper \%DATA_HASH

}

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OUTPUT: VAR{}

Replies are listed 'Best First'.
Re: Understand why dumper printed null hash
by choroba (Cardinal) on Jun 12, 2012 at 10:11 UTC
    By exposing $hash_ref to string context in $hash_ref =~ s/...//, the value has been stringified to contain something like HASH(0x82a8768). Try adding another Dumper after calling Clear.
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Re: Understand why dumper printed null hash
by Anonymous Monk on Jun 12, 2012 at 10:06 UTC

    $hash_ref=Clear($hash_ref); #Here something goes wrong.

    Yup, this is why 

    #!/usr/bin/perl --
use strict; use warnings;
use Data::Dump;
my %hash = ( 1 .. 4 );
my $hashref = \%hash;
print "$hashref\n";
dd $hashref;
$hashref =~ s/^/WHY DID I DO THIS??? /;
dd $hashref;
__END__
HASH(0x99a99c)
{ 1 => 2, 3 => 4 }
"WHY DID I DO THIS??? HASH(0x99a99c)"

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      Thank you all!

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