The problem is that you're not actually making an assignment here:
$target_tbl{
'$tcol' => { 'ctyp' => '$ttyp' ,
'clen' => '$tlen'
}
};
You can do this a couple of ways:
$target_tbl{$tcol} = { 'ctyp' => $ttyp, 'clen' => $tlen};
Note that you do *not* want to put single quotes around variables - that prevents variable interpolation, which means you'll just get the variable name as a string rather than it's value.
Another way (which I prefer) is to use hashrefs (hash reference, or a reference to a hash) all the way, e.g.:
my( $target_tbl );
$target_tbl->{$tcol}->{'ctype'} = $ttyp;
$target_tbl->{$tcol}->{'clen'} = $tlen;
Or a basically equivalent way:
$target_tbl->{$tcol} = { 'ctyp' => $ttyp, 'clen' => $tlen};
Why do I prefer using hashrefs rather than hashes of hashes? Well, hashes of hashes really are hashrefs (other than the actual variable, which is a hash), but there are some other advantages to using a hashref:
- Easier to pass around as arguments to subs
- I find the arrow syntax much clearer and more comprehensible, particularly when you get several levels deep. An example from the code I'm working on right now:
$STATS->{$var_name}->{HOURLY}->{$hour}->{max} = $hour_hi;
If that was done using an ordinary hash of hashes, it would look like this:
$STATS{$var_name}{HOURLY}{$hour}{max} = $hour_hi;
- Once you start building objects you're going to be using hashrefs a lot anyway, so why not learn them now?
Hope this helps,
Barry
________________________________________
From: Sabherwal, Balvinder (MBS) [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, June 15, 2004 01:12 PM
To: [EMAIL PROTECTED]
Subject: dynamic creation for hash of hashes
Guru's
�
Can some one pls. point out why my code is not working? I'm trying to create a hash of hashes dynamically ar the runtime with the code below.
�
Thanks
�
while ( <TL> )
{
�� chomp();
�� $tdata = $dbhs->ct_sql("select o.name , c.name , t.name,c.length
������������������������ from $opt_d..sysobjects o, $opt_d..syscolumns c, $opt_d..systypes t
������������������������ where o.name = \"$_\" and o.uid = 1
������������������������������ and o.id = c.id
������������������������������ and c.usertype = t.usertype
������������������������ order by c.name"
����������������������� );� ## Get the target columns
�
� if ( defined($errmsg) )�������� ## Make sure there were no errors in the last sql execution.
� {
�� msg_send("$opt_N","AlterRepDef.pl Failed for $opt_d db on $opt_s server" , "Script failed due to errors below.\n$errmsg\n","
$mailto","$pto");
�� exit(1);
� }
� $tlen = scalar(@$tdata) ; ## Get # of columns for the target table.
� foreach my $r (@$tdata)
� {
���� my ( $ttb , $tcol , $ttyp, $tlen ) = @$r;
���� $target_tbl{
������������������ '$tcol' => { 'ctyp' => '$ttyp' ,
��������������������������������������� 'clen' => '$tlen'
������������������������������������� }
��������������� };
���� push(@t_table,@$r);
� }
}
�
use Data::Dumper;
Dumper(%target_tbl);
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