Hi Andy,
On 8/20/12, Andy Bach <afb...@gmail.com> wrote:
> On Sun, Aug 19, 2012 at 4:48 PM, timothy adigun <2teezp...@gmail.com>
> wrote:
>> foreach my $match_value ( sort keys %stud ) {
>> print $match_value, "=", $stud{$match_value},
>> $/ if $match_value ~~ @names;
>> }
>
> "smart match" is a Perl 6 (though it probably back ported to a Perl 5
> module?) invention allowing DWIM here - look through the whole array
> for this value. In normal P5
Smart Match is introduced in Perl 5.10.1. You find more details here:
http://perldoc.perl.org/perlop.html UNDER the subheading smartmatch Operator.
> foreach my $match_value ( sort keys %stud ) {
> print "$match_value = $stud{$match_value}\n"
> if grep $match_value @names;
Smart Match is a lot faster than grep, "for-loop" and probably
"first" from List::Util Module in Perl.
While I commented on why using for loop for this kind of problem is
not effective, John's solution using map{...} is more like it and alot
better.
> }
>
> but that means you're going through @names once for each element of
> stud. Sounds like a job for a Schwartzian Transform (google it) -
> create another hash w/ @names as the keys:
> my %match_keys;
> # use a hash slice to turn elements into keys
> @match_keys{@names} = @names;
>
> and then
> foreach my $match_value ( sort keys %stud ) {
> print "$match_value = $stud{$match_value}\n"
> if defined $match_keys{$match_value};
> }
>
> I used 'defined' in case one of your names was a zero or something.
> May be a 'better' route depending upon the size of the data and/or how
> often you need to check for that name as a key.
> --
>
> a
>
> Andy Bach,
> afb...@gmail.com
> 608 658-1890 cell
> 608 261-5738 wk
>
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>
--
Tim
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