Rob Dixon wrote:
> Kenton Brede wrote:
> > __DATA__
> > user1:x:700:101:user1:/dev/null:/bin/false
> > user2:x:706:101:user2:/dev/null:/bin/false
> > user3:x:707:101:user3:/dev/null:/bin/false
> > user4:x:708:101:user4:/dev/null:/bin/false
>
> Hi Kenton.
>
> How does this look?
>
> sub get_uid {
> my %list;
> @list{map {(split /:/)[2]} <DATA>} = ();
> return (grep {not exists $list{$_}} 700 .. 799)[0];
> }
>
> More readably, this does almost the same thing:
I think there is a happy medium that harnesses the power of Perl's aggregate
tools without the obscurity of the above:
Greetings! E:\d_drive\perlStuff\JPEG>perl -w
my @uid_list = map {(split /:/)[2]} (<DATA>);
my %uid_list;
@[EMAIL PROTECTED] = ([EMAIL PROTECTED]);
my $free_number = 700;
while ($free_number < 800) {
last unless $uid_list{$free_number};
$free_number++;
}
print "$free_number\n";
__DATA__
user1:x:700:101:user1:/dev/null:/bin/false
user2:x:706:101:user2:/dev/null:/bin/false
user3:x:707:101:user3:/dev/null:/bin/false
user4:x:708:101:user4:/dev/null:/bin/false
^Z
701
You can see the reason for my preference by adding the diagnostic line:
print "$_: $uid_list{$_}\n" for keys %uid_list;
at the end of each script.
Of course, it doesn't really matter in the given context, but somehow I don't
like the idea of hash elements
hanging in that limbo of "existing but undefined". I also think that exploding
the view of that one-liner better
demonstrates each of its constituent features.
Of course, it might better demonstrate the process of assignment to a hash slice
to vary the names a bit
and call the hash a hash:
my %uid_hash;
@[EMAIL PROTECTED] = ([EMAIL PROTECTED]);
...
> sub get_uid {
>
> my %list;
>
> while(<DATA>) {
> my $uid = (split /:/)[2];
> $list{$uid}++;
> }
>
> foreach my $uid (700 .. 799) {
> return $uid unless exists $list{$uid};
> }
>
> return undef;
> }
This is definitely the most straightforward approach.
>
>
> HTH,
>
> Rob
Joseph
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