in reply to Re^2: Warning is right or not ?
in thread Warning is right or not ?

... I need the previous value of @data ...

If you mean you need to return the element in the  @data array immediately prior to the first element in the array that matches the string passed into the function, I think I would use something like this (Update: an empty string is returned if no match): 

>perl -wMstrict -le
"print get_IATA('bar');
 ;;
 sub get_IATA {
   my ($airline) = @_;
   ;;
   my @data = qw(fee fie foe foo barbell boff);
   ;;
   for my $i (1 .. $#data) {
     return $data[$i - 1] if $data[$i] =~ m{ \A \Q$airline\E }xms;
     }
   return '';
   }
"
foo

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Update: Here's a variation that returns every element in the  @data array immediately prior to an element in the array that matches the string passed into the function. An empty list is returned if no match. 

>perl -wMstrict -le
"printf qq{'$_' } for get_IATA('bar');
 ;;
 sub get_IATA {
   my ($airline) = @_;
   ;;
   my @data = qw(fee fie yyy barfly foe fum zzz barbell foo);
   ;;
   return
     map { $data[$_] =~ m{ \A \Q$airline\E }xms ? $data[$_ - 1] : () }
     1 .. $#data
     ;
   }
"
'yyy' 'zzz'

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Re^4: Warning is right or not ?
by Anonymous Monk on Dec 23, 2012 at 19:13 UTC

    Thank you very much for your tips. With my irregual data I had to change my code( and data) and your tips helped alot.

    In my check table (csv), I have 3 character codes(ICAO) and their equivalent 2 character codes(IATA) and descriptions. At first, IATA was at first column so I needed previous element of the array when the key was found. But after having an example of irregular ICAO code, which has 2 characters that matches its IATA code, the code didn't help since Perl stops after the first matching. And that IATA code is used three times in the table ( 1 ICAO, 2 IATA)

    Then I changed IATA and ICAO columns' order and changed the code with your help and now it works. Though it may be clumsy, i think its pretty clear. 

    
--$hash{'AirIATA'}= get_IATA($airlineLoc,$hash{'Airline'}) ;

-------------------------------------------------------

sub get_IATA
{
        my $file = shift;
        my $airline = shift;
        my @data;

        open(my $fh, '<', $file) or die "Can't read file '$file' [$!]\
+n";

        while (my $line = <$fh>)
        {
                my @fields = split(/;/, $line);
                push @data, @fields;
        }
        close($fh);

        my @results=    map
                {
                        $data[$_] =~ m{ \A \Q$airline\E }xms ? $data[$
+_ + 1] : ()
                }
                1 .. $#data;
        if ($#results>1)
        {
                return $results[1];
        }
        elsif ($#results>0) # Do I need a second check, like <2 ?
        {
                return $results[0];
        }
        else
        {
                print "Airline $airline has no definition in $file fil
+e\n";
                exit; # Program should stop if there is no match
        }
}

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