in reply to Confused by a Conditional

delete

Tiptoeing up to a Perl hacker.
Dave AKA damian

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Re: Confused by a Conditional
by Abigail (Deacon) on Jun 10, 2001 at 18:09 UTC
    You are very, very wrong. 
    'ID' or 'TITLE' or 'GENE' or 'CYTOBAND' or 
'LOCUSLINK' or 'CHROMOSOME' or 'SCOUNT'

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    evaluates to 'ID'. 
    use strict;
my $key = 'TITLE';

unless (($key) eq ('ID' or 'TITLE' or 'GENE' or 'CYTOBAND' or 
                   'LOCUSLINK' or 'CHROMOSOME' or 'SCOUNT')) {
    print "Damian is wrong\n";
}

    [download]
    This prints "Damian is wrong".

    -- Abigail

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Re: Re: Confused by a Conditional
by ZZamboni (Curate) on Jun 10, 2001 at 20:12 UTC
    The only way the conditional in your snippet evaluates to true is if $key=='ID'. Try setting $key to 'GENE', for example (which is one of the valid values), and you'll see.

    --ZZamboni

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      delete

      Tiptoeing up to a Perl hacker.
      Dave AKA damian
[reply]

        This prints oh for me, just as I would expect. ActivePerl 5.005_03 on Win2K.

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Re: Re: Confused by a Conditional
by CheeseLord (Deacon) on Jun 10, 2001 at 12:23 UTC

    I admit, that's pretty cool. But I personally like this just a bit better (only because it takes up less space on the line):

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

my $key = 'JUMP';

if ($key =~ /^(ID|TITLE|GENE|CYTOBAND|LOCUSLINK|CHROMOSOME|SCOUNT)$/) 
+{
   print "I don't know why this is printing.\n";
}

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    I think there's someway that might be broken, though, if I remember my reading on regexes... but if you chomp everything right, I think it will accomplish the same thing (with the added benefit(?) of placing exactly what it matched in $1).

    CheeseLord

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