title: Change key in associative array in PHP
body: <p>Say I have an array like this:</p>
  
  <pre><code>array(2) {
    [0]=&gt; array(2) {
      ["n"]=&gt; string(4) "john"
      ["l"]=&gt; string(3) "red"
    }
    [1]=&gt; array(2) {
      ["n"]=&gt; string(5) "nicel"
      ["l"]=&gt; string(4) "blue"
    }
  }
  </code></pre>
  
  <p>How would I change the keys of the inside arrays? Say, I want to change "n" for "name" and "l" for "last_name". Taking into account that it can happen than an array doesn't have a particular key.</p>