Hash table issue

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

Hi Monks , I have this littel issue and need your help. I have the following loop that is reading input and inserting it inside a hash table:

my $x=1;
while($x <= $EMPnum)
{
    
    my $t1 = $left1->Label(-text=>"Guy #$x",
    -background=>'gray')->pack();

    my $num = $left2->Entry(-width=>12,
        -background =>'white',
        -borderwidth=>2,-relief=>'sunken',
        -textvariable => \$info{EmpNum}[$x])->pack();
    
$x++;
}
[download]

I am having problem printing the output of the hash $info{EmpNum} , I am trying the following :

 
foreach (@{$info{EmpNum}}) {
 print "\t$info{$_}>[0]          $info{$_}->[1]\t$info{$_}->[2]\t$info
+{$_}->[3]\n";
             }
[download]

but it gives me nothing . thanks

Comment on Hash table issue Select or Download Code

Replies are listed 'Best First'.
Re: Hash table issue by Zaxo (Archbishop) on May 08, 2004 at 21:28 UTC
You have a couple of errors in your print loop, corrected below `foreach (keys %info) { print "\t$info{$_}->[0]\t$info{$_}->[1]\t$info{$_}->[2]\t$info{$_} +->[3]\n"; }` [download] You can clean it up further like this, `for (values %info) { print "\t", join("\t", @$_), "\n"; }` [download] After Compline, Zaxo	[reply] [d/l] [select]
Re: Re: Hash table issue by Anonymous Monk on May 08, 2004 at 21:42 UTC
thanks Zaxo , but the issue I am still having is I am using the same hash table for somthing elese . Is it better to create a new hash table or can I do the following : `foreach (keys %info{EmpNum}) { print "\t$info{$_}->[0]\t$info{$_}->[1]\t$info{$_}->[2]\t$info{$_} +->[3]\n"; }` [download] I have $info{time} , $info{list} ...just wondering if I can use the same one. thanks	[reply] [d/l]
Re: Re: Re: Hash table issue by Zaxo (Archbishop) on May 08, 2004 at 21:55 UTC
You seem to be confused about references and dereferencing data structures. For a quick once-over, see References quick reference. For more depth, see perlref, perllol, perldsc and others. After Compline, Zaxo	[reply]
Re: Hash table issue by krusty (Hermit) on May 08, 2004 at 21:36 UTC
From the looks of your code, you have a hash %info, which contains only one key "EmpNum" and the value associated with that key is a reference to an anonymous array. At no point in time do I see you populating the elements of your anonymous array, but instead I see you passing a reference to `$info{EmpNum}[$x]` where $x is some index value you increment. Is there even such an element `$info{EmpNum}[1]`? Nor do I see you creating any other keys to this hash `%info` except for "EmpNum". So I don't see what array you are iterating through when you do your foreach loop or what you are printing out.	[reply] [d/l] [select]
Re: Hash table issue by Errto (Vicar) on May 09, 2004 at 00:32 UTC
I don't know Tk all that well but I assume that `-textvariable` expects to be given a reference to where it will eventually store the value from that widget. As written, it will store these in successvie elements of `@{$info{EmpNum}}`. I'm going to assume you have some valid reason for creating this array as a reference value in a hash with no other keys, rather than an ordinary array. However, your `foreach` loop doesn't look right. What you are iterating over are the elements of the array, `@{$info{EmpNum}}` yet you are treating each of these as if it is a key in %info that in turn returns an array of four elements. If true, then I have to assume this happens somewhere else, because your first block of code doesn't create anything like that. In any case you have a typo. `$info{$_}>[0]` should be `$info{$_}->[0]` or simply `$info{$_}[0]`. Update: I didn't fully read the thread above before posting. You can certainly do: `foreach (keys %info) { print "\t$info{$_}->[0]\t$info{$_}->[1]\t$info{$_}->[2]\t$info{$_} +->[3]\n"; }` [download] Note the change from what you posted (%info instead of %info{EmpNum}). But again, given the code you posted, this will print only one row, because the only key in %info is 'EmpNum'	[reply] [d/l] [select]