#!/usr/bin/perl
use strict;
use warnings;

my @asdf = ();
print "hi\n" if ($#asdf);
print "howdy\n" if (scalar @asdf);
print "hola\n" if ($asdf[0]);
print "---\n";

@asdf = ('a');
print "hi\n" if ($#asdf);
print "howdy\n" if (scalar @asdf);
print "hola\n" if ($asdf[0]);
print "---\n";

@asdf = ('','a');
print "hi\n" if ($#asdf);
print "howdy\n" if (scalar @asdf);
print "hola\n" if ($asdf[0]);

__END__
Output:

hi
---
howdy
hola
---
hi
howdy