Re: How to determine if an array passed as an argument to a subroutine is zero-length

w/o seeing some code its tough to know exactly what you are asking.... Here is one attempt to answer your question.

#!/usr/bin/perl -wT
use strict;

my @arr  = qw(a b c d e);     # make a non-empty array
my @arr2 = qw();              # make an empty array

my $val  = isempty(\@arr);    # check if arr isempty
my $val2 = isempty(\@arr2);   # check if arr2 isempty

print "\@arr ",  $val  ? 'is' : 'is not', " empty.\n";
print "\@arr2 ", $val2 ? 'is' : 'is not', " empty.\n";

sub isempty {
   my $aref = shift;          # get array ref as param
   return !@$aref;            # check array for emptiness
}

=output
@arr is not empty.
@arr2 is empty.
[download]

-Blake

Comment on Re: How to determine if an array passed as an argument to a subroutine is zero-length Download Code

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Re: Re: How to determine if an array passed as an argument to a subroutine is zero-length by Withnail (Novice) on Sep 07, 2001 at 21:06 UTC
Thanks for your input, people! Sorry about the lack of code example before. Here's what I've come up with so far: `get_highest_vers(\@vers); sub get_highest_vers { my $vers_index; my @sorted_vers; my @locvers = @_; $#sorted_vers = -1; if ($#locvers == -1) { $highest_vers = 0.00; } else { for ($vers_index = 0; $vers_index <= $#locvers; $vers_index++) { $locvers[$vers_index] =~ s/\.\/v//; $locvers[$vers_index] += 0; } # Sort the archive version numbers and grab the highest one @sorted_vers = sort {$b <=> $a} @locvers; $highest_vers = shift(@sorted_vers); } ($major, $minor) = split(/\./, $highest_vers); }` [download] This seems to work, (although I can't help feeling it's a little ornate!) Anyway, I'm still having problems when I try and move the subroutine to a seperate module and call it in using the "use Module" construct: I get a complaint that the argument given in the subroutine call should be an array, not a reference constructor. It also says that no implicit dereferencing is allowed--use the {EXPR} forms as an explicit dereference. Can anyone advise? BTW, I'm using "diagnostics" and "strict". -Withnail	[reply] [d/l]

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Re: Re: How to determine if an array passed as an argument to a subroutine is zero-length
by Withnail (Novice) on Sep 07, 2001 at 21:06 UTC

Sorry about the lack of code example before. Here's what I've come up with so far:

get_highest_vers(\@vers);

sub get_highest_vers {
  my $vers_index;
  my @sorted_vers;

  my @locvers = @_;

  $#sorted_vers = -1;

  if ($#locvers == -1) {
    $highest_vers = 0.00;
  } else {
    for ($vers_index = 0; $vers_index <= $#locvers; $vers_index++) {
      $locvers[$vers_index] =~ s/\.\/v//;
      $locvers[$vers_index] += 0;
    }
    # Sort the archive version numbers and grab the highest one
    @sorted_vers     = sort {$b <=> $a}  @locvers;
    $highest_vers    = shift(@sorted_vers);
  }
    ($major, $minor) = split(/\./, $highest_vers);
}
[download]

This seems to work, (although I can't help feeling it's a little ornate!)

Anyway, I'm still having problems when I try and move the subroutine to a seperate module and call it in using the "use Module" construct:

I get a complaint that the argument given in the subroutine call should be an array, not a reference constructor. It also says that no implicit dereferencing is allowed--use the {EXPR} forms as an explicit dereference.

Can anyone advise? BTW, I'm using "diagnostics" and "strict".

-Withnail

[reply]
[d/l]