In article <[EMAIL PROTECTED]>,
[EMAIL PROTECTED] (Rob Richardson) writes:
>Greetings!
>
>In the train schedule program that you are all probably heartily sick
>of by now, I have added a ScheduleDay class that represents all trains
>running on a given day. It has a method that returns an array of
>references to all of the Train objects for that day. I want to sort
>those trains on the times people have to show up for them. The Train
>class has a GetCrewCall() method that returns a string containing the
>crew call time in HH:MM form, with two digits guaranteed for the hours.
> Thus, "cmp" will suffice for the comparison. But I'm not sure how to
>set up the sort. Here's what I have:
>
>sub GetTrainsByTime
>{
> my $self = shift;
> my @result;
> my @temp;
> my $aTrain;
> my $aTrainName;
>
> # First we build a temporary array of references to trains
> foreach $aTrainName (keys $self)
^ % missing
> {
> push @temp, $self{aTrainName};
^ $ missing
> }
>
> @result = sort {$a->GetCrewCall() cmp $b->GetCrewCall()} @temp;
> return @result;
>}
(1) If you wanted to put the keys of a hash into an array, just do it
all at once:
@temp = keys %$self
(2) If you want to sort the keys of a hash, there's no need to put
them into an array. sort takes a list as input:
return sort { $a->GetCrewCall cmp $b->GetCrewCall } keys %self
>I'm pretty sure this will work, since $a and $b will be references to
>Train objects, and whatever is inside the brackets is just a plain
>ordinary block of code. Is this correct?
Yes.
>In general, $a and $b are going to be elements of the array being
>sorted, aren't they?
Yes.
--
Peter Scott
http://www.perldebugged.com
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