How can I merge id all value in multidimension array into one array
<p>I have an array like this : </p>

<pre><code>[0] =&gt; Array
    (
        [id] =&gt; 13

        [children] =&gt; Array
            (
                [0] =&gt; Array
                    (
                        [id] =&gt; 14
                        [parent_id] =&gt; 13

                    )

                [1] =&gt; Array
                    (
                        [id] =&gt; 15
                        [parent_id] =&gt; 13

                    )


            )

    )
</code></pre>

<p>How can I get all [id] from this array and input them to one array like that :</p>

<pre><code>    $arr = array(13,14,15)
</code></pre>

<p>Thanks for any help !</p>
