how to set default value for array（php）
<p>e.g:</p>

<pre><code>$arr = array('k1'=&gt;1,'k2'=&gt;2,'k3'=&gt;3);
</code></pre>

<p>If i want get $arr['k4'] (unexpect index),there is a notice:</p>

<pre><code>Notice: undefined index......
</code></pre>

<p>so,can i set a dufalut value for array,like as ruby's hash:</p>

<pre><code>h = {'k1'=&gt;1,'k2'=&gt;2,'k3'=&gt;3}
h.default = 'default'
puts h['k4']
</code></pre>

<p>then,i'll get 'default';</p>
