PHP accessing an array

I'm a bit confused.

I have an array:

<?php 

$terms = get_the_terms($post->ID, 'pf');
        print_r($terms);
?>

And it outputs:

Array ( [15] =开发者_如何学运维> stdClass Object ( [term_id] => 15 [name] => Text [slug] => text [term_group] => 0 [term_taxonomy_id] => 33 [taxonomy] => pf [description] => An PF article. [parent] => 0 [count] => 3 [object_id] => 694 ) )

And I want just to output slug ("text" in this case) instead of the whole array.

So I'm doing:

<?php $terms = get_the_terms($post->ID, 'pf');
             echo $terms["slug"]; ?>

And it outputs nothing.

This gives no results as well:

echo "{$terms['slug']}";

Any ideas?

UPDATED!!!

I can't use $term[15]->slug since my script will be based on [taxonomy] (pf in this case)! :) So it's impossible to do that without foreach loop?

---

terms array 15 index contain object access like this

echo $term[15]->slug

---

there is stdclass object at index 15 of the inside arry which can be converted/accessed as array by casting but try this insted

$term[15]->slug

---

Following up on Pekka's answer, if you reformat your print_r() output, you'd get:

Array (
    [15] => stdClass Object (
        [term_id] => 15
        [name] => Text
        [slug] => text
        [term_group] => 0
        [term_taxonomy_id] => 33
        [taxonomy] => pf
        [description] => An PF article.
        [parent] => 0
        [count] => 3
        [object_id] => 694
    )
)

When dumping out a variable with print_r(), it's good practice to surround the call with <pre> tags - print_r doesn't do any HTML-ification of the data, so the nice indentation it does with arrays gets lost when viewed in an HTML page. Using the <pre> tags preserves the formatting. using var_dump() will do the same, but also add type/size data to the dump output.