title: Get match keys from an array
body: <p>I have a specific key in array that I would like to get, however it is suffix by an incremental counter.</p>
  
  <pre><code>Array
  (
    [nombre] =&gt; Carlos
    [apellido] =&gt; Delfino
    [sum1] =&gt; Array
              (
                [0] =&gt; Apple
                [1] =&gt; Banana
                [2] =&gt; Liquor
              )
    [sum3] =&gt; Array
              (
                [0] =&gt; Grapes
              )
  )
  </code></pre>
  
  <p>I am planning to put the <code>sum</code> keys (sum1 &amp; sum3) on a new array. A <code>foreach</code> is on my mind however I am doubting should I use regex or PHP string function for this.</p>
  
  <pre><code>foreach($arr as $k =&gt; $v)
  {
    //I'm lost here on how to match keys with at least `sum` word on it
  }
  </code></pre>