use CGI.pm

This will give you access to params without having to know if they came in on a post or a get and without having to monkey around with environment variables.

As for your code snipit:

foreach $thing (keys(%INPUT)) {
        if(ref($INPUT{$thing}) eq "ARRAY") { $INPUT{$thing} = join('^'
+, $$INPUT{$thing}); }
#       if($#INPUT{$thing}) { $INPUT{$thing} = join('^', $$INPUT{$thin
+g}); }
}
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The line starting with a pound is a comment, but I suspect you knew that. (Its also wrong... you can't $# a hash.) So I'm going to drop it and just look at the other line. Thats trying to dereference an array, which you might want to do explicitly:

foreach $thing ( keys %INPUT ) 
{
    if( ref( $INPUT{$thing} ) eq "ARRAY" ) 
    { 
        $INPUT{$thing} = join '^', @{$INPUT{$thing}}
    }
}

# You can also write the above like this:
$INPUT{$_} = join '^', @{$INPUT{$_}} for grep {"ARRAY" eq ref $INPUT{$
+_}} keys %INPUT
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