Question

A newborn Perl developer here. I’ve been wracking my brain and searching all over online trying to figure this out… exasperated, I am come to you seeking clarity.

I have the following code (only relevant parts left in) as rest is working):

my @arrMissingTids;
@arrMissingTids = %hshTids;

my $missingtid;
foreach $missingtid (@arrMissingTids) {
    print "$missingtid\n";
}

This works well, returning the values I want to be in the array:

500000246,500000235,500000185,500000237,500000227,500000252

However, when I pass this to a subroutine and include it in a variable name, it does not provide the list as written above, but rather just the number 1. Code for that is below:

myqry(@arrMissingTids);

sub myqry($) {

    my $missingtids = @_;

    $sql = "select 
        i.tid i_tid, i.name i_name
        from 
        instrument i
        where i.tid in ($missingtids)";

    print "$sql/n";
}

Print $sql returns the following:

Select i.tid i_tid, i.name i_name from instrument i where i.tid in (1)

When I want it to return the following:

Select i.tid i_tid, i.name i_name from instrument i where i.tid in (500000246,500000235,500000185,500000237,500000227,500000252)

Thanks in advance for any pointers in the right direction!

Answer 1

The problem is right here:

my $missingtids = @_;

You’re calling the array @_ in scalar context. That means that you’re assigning to $missingtids the number of elements in @_. One way to work around this would be to pass an array reference:

sub myqry {

    my $missingtids_ref = shift;
    my @missingtids=@$missingtids_ref;

    $sql = "select 
        i.tid i_tid, i.name i_name
        from 
        instrument i
        where i.tid in (" . join(",",@missingtids) . ")";

    print "$sql/n";
}

For more information, take a look at perldoc perlref and perldoc perldata.