• Variable starts with a $: You're asking for a "scalar" value.
• Variable starts with a @: You're asking for an array of scalars.
• Variable starts with a %: It's a hash.
• Square braces - [ and ] - with the variable often indicates that you're accessing an array element.
• Curly braces - { and } - with the variable names means you're trying to access a hash element.

$secretword=$words{$name};
[download]

If you had use strict at the top of your program, you would have received a fatal error for trying to access a "words" hash that was undeclared. Actually, you would have gotten errors earlier when you tried to assign elements to the @words array. I know that's not covered right away in the book you are using, but it's a good practice to get into (along with using warnings, the -w switch). Using strict and warnings will save you many hours of debugging and, in this case, an error would have occured long before it did, thus allowing you to have a better idea what's actually causing the error.

Unfortunately, the above information is a very simplistic treatment of the issues, but it's some good stuff to always keep in mind when you are first starting out.

Cheers,
Ovid

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First off, in your first line you're defining an array "@words" when what I think you want is a hash, "%words". Below, in the "$words{$name}" part, that wouldn't work as a lookup with the array @words, which is what you have now. Change the "@" to a "%" and your code should work.

I guess the thing to learn here is that problems aren't always obvious. If you start developing your scripts with use strict; and  perl -wT it will initially seem like a pain in the butt (but) problems like this will just pop out at you.

Good luck!

Here's your "llama" code, fixed.

#!/usr/bin/perl
use strict;

my(%words,$name,$secretword,$words,$guess);

%words=qw(
    fred  camel
    barney  llama
    betty  alpaca
    wilma  alpaca
);
print "What is your name?\n";
$name=<STDIN>;
chomp ($name);
if ($name eq "Randal")
{
    print "Hello, Randal! Welcome!\n"
} else {
    print "Hello $name.\n";
    $secretword=$words{$name};       # use {} for hash
    if ($secretword eq ""){          # gives me an error around here
        $secretword="stupid";      #default secret word
    }
    print "What is the secret word?";
    $guess =<STDIN>;
    chomp($guess);
    while ($guess ne $secretword){
        print "Wrong, try again.\n";
        $guess=<STDIN>;
        chomp ($guess);
    }
}
[download]

That code, while it found the main code error, will still sometimes show the error message.

$secretword=$words{$name};
if ($secretword eq ""){
  $secretword="stupid";
}
[download]

If $name is not found in the hash %words, then $secretword will be undefined and will produce the error mentioned when used as if defined. If you however test for the definedness of $secretword you will be closer to the original aim.

if (defined $secretword) {
  $secretword = 'stupid';
}
[download]

In perl style I'd probably write:

$secretword = $words{$name} || 'stupid';

But that is a matter of choice.

This example in llama2 will not be in llama3. I can speak with authority on that. {grin}

-- Randal L. Schwartz, Perl hacker