Thanks Uri. That makes perfect sense.
-----Original Message-----
From: Uri Guttman [mailto:u...@stemsystems.com]
Sent: Wednesday, May 25, 2011 1:37 PM
To: Tim Lewis
Cc: beginners@perl.org
Subject: Re: Basic question on arrays $ vs @
>>>>> "TL" == Tim Lewis <twle...@sc.rr.com> writes:
TL> This is a very basic question on arrays and referring to the
TL> elements. In referring to the elements, I know that it is correct
TL> practice to use $ instead of @, but I know that Perl allows the @.
TL> My simple question is what is the difference. I have looked at
TL> different Perl tutorials, but have not found one that explains why
TL> to use $ over @. Is it just common practice, or is there a
TL> functional reason? Tim
TL> Quick example:
TL> my @animals = ("dog","cat");
TL> my $arrayCounter = @animals;
TL> for (my $count=0;$count<$arrayCounter;$count++) {
TL> print "Critter is $animals[$count]\n"; # use $animals instead of
@animals
TL> }
the sigil is supposed to tell you how many elements you are getting from
the array. $animals[0] is obviously one elements. @animals[0,1] is
getting two elements and is called a slice. so @animals[0] is also a
slice and is legal but misleading, it should use a $ for the
sigil. where slices really come into play and can legimaitely get one
element is when the the indexes are in an array. then you need the @
sigil as the index is also in list context (the prefix sigil does
provide the context for inside the []).
@indexes = ( 0 ) ;
print @animals[@indexes] ; # prints 'dog'
note that if you use a $ like this:
print $animals[@indexes] ; # prints 'cat'
it prints cat since @indexes in scalar context is 1 which is the index
used to get cat.
so there is a warning in perl if you use a scalar (single literal value
or scalar var) when indexing an array slice. it means you chose a list
context for indexing but explicitly indexed with one value. yes, it
works and is legal but it is not good coding.
uri
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