title: Cycle all array's keys
body: <p>Shame to ask, but I dont know how to echout all array's keys in this foreach cycle:</p>
  
  <pre><code>$i=0;
  foreach ($matches as $match) {
  echo $match[$i++];
  }
  </code></pre>
  
  <p>Right now result is just "1". Instead of 1 2 3 7</p>
  
  <pre><code>Array
  (
      [0] =&gt; Array
          (
              [0] =&gt; 1
              [1] =&gt; 2
              [2] =&gt; 3
              [3] =&gt; 7
          )
  
  )
  </code></pre>