Perl throws an error message about syntax

Question

So, building off a question about string matching (this thread), I am working on implementing that info in solution 3 into a working solution to the problem I am working on.

However, I am getting errors, specifically about this line of the below function:

next if @$args->{search_in} !~ /@$cur[1]/;

syntax error at ./db_index.pl line 16, near "next "

My question as a perl newbie is what am I doing wrong here?

sub search_for_key
{
    my ($args) = @_;

    foreach $row(@{$args->{search_ary}}){
        print "@$row[0] : @$row[1]\n";
    }

    my $thiskey = NULL;
    foreach $cur (@{$args->{search_ary}}){
        print "\n" . @$cur[1] . "\n"
        next if @$args->{search_in} !~ /@$cur[1]/;
        $thiskey = @$cur[0];
        last;
    }
    return $thiskey;    
}

Answer 1

You left off the semicolon at the end of the previous line. That's what caused the syntax error, anyway. I think you're also misusing $args, but it's hard to be sure about that without knowing how you're calling this function.

Answer 2

Side note, are you sure you can't just use a hash for what you're doing? It seems awfully complicated do do something so simple:

my %hash = ( 
     key1 => 'value1',
     key2 => 'value2',
);

exists $hash{$search_in};   # true/false.
my $result = $hash{$search_in}; # returns 'value1' when $search_in is 'key1'

Or if you need to search by value:

my %flip = reverse %hash;
$result = $flip{$search_in};

And if you really need a regex key ( or value ) lookup:

 sub string_match {
        my ($lookup_hash, $key ) = @_;
        for my $hash_key ( %{ $lookup_hash } ){ 
            return $hash_key if $key =~ $lookup_hash->{$hash_key};
        }
        return; # not found.
 }
 my $k = string_match({
           'whitespace at end' =>  qr/\s+$/,
           'whitespace at start' => qr/^\s+/,
 }, "Some Garbage string     ");  # k == whitespace at end 

Answer 3

There are several issues here.

1. Are you adding use strict; and use warnings; at the top of your script before you do anything else? You only posted the sub, but it is clear that you are not using these.

2. What is NULL? (strict will not let you use bare-words...) Be sure to read What is Truth in Perl? The more Perly way is to deal with "truth" or "false" is defined / undef or exists or specifically test for a value chosen as a convention.

3. Missing ; after print "\n" . @$cur[1] . "\n"

4. Your data structures seem way too complicated. From what I can tell, you are passing a reference to a hash of arrays, true? Why your data structures get really obscure, back up and look at what you are trying to do...

5. Perl gives you plenty of way to shoot yourself in the foot. It is not strictly typed and you will do yourself (and your readers) a favor by naming references as a derivative of what they refer to. So instead of $args use $ref2HoArefs for example.