in reply to Re: How to combine these 2 subroutines in one?
in thread How to combine these 2 subroutines in one?

Thanks to both of you!
I have tried this,which works if I pass the array as array, but why can't I make it work if I pass the array as reference to array
sub clean_list {

    my $type_of_arg=ref(\@_);

    my @array_with_duplicates=(@_);
    my @array_no_duplicates;

    if($type_of_arg eq 'ARRAY')        #if the list is passed as an ar
+ray
    {
        my $previous = '';
        while (scalar @array_with_duplicates > 0) 
        {
               my $next = shift(@array_with_duplicates);
               if ($previous ne $next) 
               {
                 push(@array_no_duplicates, $next);
                 $previous = $next;
               }
        }
    }

    elsif($type_of_arg eq 'REF')    #if the list is passed as a refere
+nce to an array
    {
        my %hash;
          @hash{@{$_[0]}}=();
          #@{$_[0]}=keys %hash;
          @array_no_duplicates=keys %hash;
    }

    return (@array_no_duplicates);
}

open(IN, '<', 'ex5.acc') or die "Could not read file\n";
my @initial_array = <IN>;
close IN;
@initial_array = sort @initial_array;

my @final_array = clean_list(@initial_array);  #this works
# @final_array = clean_list(\@initial_array);  #this does not work
# Save the clean table
open(OUT, ">", "ex5.acc.CLEAN") or die "Could not create file\n";
print OUT @final_array;
close OUT;

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Re^3: How to combine these 2 subroutines in one?
by Athanasius (Archbishop) on Apr 03, 2014 at 13:45 UTC

    Two obvious problems (there may be others):

    • @_ is the array of arguments passed into the subroutine, so \@_ will always be an array reference. You need ref($_[0]) which tests the first argument (but see my answer above as to why this may not be the best approach).

    • If the array is passed in as a reference, $type_of_arg will be the string 'ARRAY', indicating an array reference. If the array is passed in as a list (and if the first element of that list doesn’t happen to be a reference), $type_of_arg will be the empty string, not 'REF'. Again, see ref.

    Hope that helps,

    Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

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      Aha, I see, will look further in my code, thank you for the tips :)
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        Ok, I tried this
        sub clean_list {


    my $type_of_arg=ref(@{ $_[0] });

    print "Type of argument passed is: $type_of_arg\n";
}
open(IN, '<', 'ex5.acc') or die "Could not read file\n";
my @initial_array = <IN>;
close IN;
clean_list(@initial_array); 
clean_list(\@initial_array);

        [download]

        and, if I pass the list as a reference it works OK, whereas, if I pass it as a simple array I get:
        Can't use string ("L13923") as an ARRAY ref while "strict refs" in use
+ at Lesson10.pl line 32.

        [download]
        The L13923 is the first id that I have in my input file...
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