Yes, by printing out the last index (element of the array) you find the
number of elements (or current index in a loop). Additionally, when
undefined (no elements) it returns "-1", which is what is happening in
this case, since the key is not used to create an element. However, I
haven't found that a string of digits is not allowed to be a hash key,
which I think is actually the problem. That is, thanks to Kevin who
presented below the result from using strict refs. ---rod
Kevin Buettner wrote:
> On May 23, 2:03pm, Kevin Buettner wrote:
>
>
>>I was puzzled about what exactly ``print $#{keys %addresses}'' is doing.
>>What I think is happening is that ``keys %addresses'' is getting converted
>>into a scalar and you're seeing the last array index of the array by that
>>name. Here's an example which should make this somewhat more clear:
>>
>>$ perl -e '@aa = (1,2,3); print $#{'a' . 'a'}; print "\n";'
>>2
>
>
> I've done a little more digging... $#{keys %addresses} is an example
> of a "symbolic reference". (See the perlref man page for more
> information.) It's instructive to put "use strict 'refs'" at the
> beginning of Roderick's original example. E.g,
>
> $ perl -e 'use strict "refs"; $lineref->[0] = "00401000"; $addresses{"$lineref->[0]"} =(defined @cmdNode ? $#cmdNode : 0); print $#{keys %addresses};'
> Can't use string ("1") as an ARRAY ref while "strict refs" in use at -e line 1.
>
> So, ``print $#{keys %addresses}'' is printing out the index of the last
> element of the array named "1".
>
> Kevin
> ________________________________________________
> See http://PLUG.phoenix.az.us/navigator-mail.shtml if your mail doesn't post to the list quickly and you use Netscape to write mail.
>
> PLUG-discuss mailing list - PLUG-discuss@lists.plug.phoenix.az.us
> http://lists.PLUG.phoenix.az.us/mailman/listinfo/plug-discuss
(text/plain)