declaring a zero size hash

[Dukelow, Don]

I'm trying to declare a zero size hash so a sub function can populate it and
be see by all other sub's.

my %loginHash();

But the use strict doesn't like it.  All examples of making a hash
structure is hard coded in the program or is made reading from a file.  When
I try to run the script all I get is syntax error near %loginHash(
What am I missing?

Don Dukelow


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Re: declaring a zero size hash

[Jeff Pang]

Just write it like:

my %loginHash = ();

This should work.

-Original Message-
From: Dukelow, Don [EMAIL PROTECTED]
Sent: Dec 13, 2006 12:23 AM
To: beginners@perl.org
Subject: declaring a zero size hash

I'm trying to declare a zero size hash so a sub function can populate it and
be see by all other sub's.

my %loginHash();



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Re: declaring a zero size hash

[Adriano Ferreira]

On 12/12/06, Dukelow, Don [EMAIL PROTECTED] wrote:

I'm trying to declare a zero size hash so a sub function can populate it and
be see by all other sub's.

my %loginHash();


 my %loginHash;

should be enough.


But the use strict doesn't like it.


It is not use strict that does not like it. It is Perl itself --
this is a syntax error:

 $ perl -e 'my %h();'
 syntax error at -e line 1, near %h(
 Execution of -e aborted due to compilation errors.


All examples of making a hash
structure is hard coded in the program or is made reading from a file.  When
I try to run the script all I get is syntax error near %loginHash(
What am I missing?


Something like this might do what you want:


# read a file and store each line at a bucket of a hash
sub pop_hash {
  my $h = shift; # the hash ref
  my $f = shift; # the filehandle
  while ($f) {
  $h-{$.} = $_;
  }
  return $h; # but it was already changed in-place
}

my %h;
pop_hash(\%h, *STDOUT);
use Data::Dumper;
print Dumper(\%h);

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Re: declaring a zero size hash

[Tom Phoenix]

On 12/12/06, Dukelow, Don [EMAIL PROTECTED] wrote:


I'm trying to declare a zero size hash so a sub function can populate it and
be see by all other sub's.

my %loginHash();


Maybe you mean this?

   my %loginHash = ();

But every new variable (which is what 'my' is declaring) starts out
empty, so all you really need is this:

   my %loginHash;

Hope this helps!

--Tom Phoenix
Stonehenge Perl Training

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RE: declaring a zero size hash

[Helliwell, Kim]

I think you need to do:

my %loginhash = {};

Kim Helliwell
LSI Logic Corporation
Work: 408 433 8475
Cell: 408 832 5365
[EMAIL PROTECTED]
 
Please Note: My email address changed to [EMAIL PROTECTED] on Oct
14. The old email address ([EMAIL PROTECTED]) will stop working after
Jan 15, 2007. Please update your address book and distribution lists
accordingly. Thank you.
-Original Message-
From: Dukelow, Don [mailto:[EMAIL PROTECTED] 
Sent: Tuesday, December 12, 2006 8:23 AM
To: beginners@perl.org
Subject: declaring a zero size hash

I'm trying to declare a zero size hash so a sub function can populate it
and
be see by all other sub's.

my %loginHash();

But the use strict doesn't like it.  All examples of making a hash
structure is hard coded in the program or is made reading from a file.
When
I try to run the script all I get is syntax error near %loginHash(
What am I missing?

Don Dukelow

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Re: declaring a zero size hash

[Adriano Ferreira]

On 12/12/06, Helliwell, Kim [EMAIL PROTECTED] wrote:

I think you need to do:

my %loginhash = {};


That's not right. {} is a hash ref, not a hash. It stands for a scalar value.

When you do that

   my %h = {}

or, for the same result,

   my %h = 1;
   my %h = abacate;

you end with a hash with one pair, whose key is the given scalar and
the value is undef.

See the output of

  $ perl -MData::Dumper -e '%h = {}; print Dumper(\%h)'
  $VAR1 = {
'HASH(0x10240170)' = undef
  };


Kim Helliwell
LSI Logic Corporation
Work: 408 433 8475
Cell: 408 832 5365
[EMAIL PROTECTED]


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