$ perl -we 'my $h={k=>undef}; print $h->{k} if exists $h->{k}'
Use of uninitialized value in print at -e line 1.
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This is why defined() may be preferable.

 my $value = "<results>
                <name>$args->{name}</name>
                <address>$args->{address}</address>
                ...
              </results>
              ";
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my ($args) = @_;
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Would be possible to have it without a loop

What's wrong with loops? They're low in fat, high in fiber... oh, nevermind.

use warnings;
use strict;

my $info = send_values({
    name    => 5,
    address => 6,
    id      => 7,
    pic     => 8,
});

print $info;


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

    my @params = qw(
        name
        address
        pic
        id
        zip
        phone
    );
    my $values = "<results>\n";
    for (@params) {
        $values .= "      <$_>$args->{$_}</$_>\n" if exists $args->{$_
+};
    }
    $values .= "</results>\n";
    return $values;
}


__END__

<results>
      <name>5</name>
      <address>6</address>
      <pic>8</pic>
      <id>7</id>
</results>
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You could do the above without a loop, but it wouldn't be as scalable or as easy to maintain. For example, you would have to type 'address' 4 times instead of once:

        $values .= "      <address>$args->{address}</address>\n" if ex
+ists $args->{address};
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