title: Passing by reference to shuffle() does not work / built-in functions joining in PHP
body: <p>An aspect of PHP:   </p>
  
  <pre><code>$numbers = shuffle(range(11, 20));
  </code></pre>
  
  <p>This will not work. It produeces a "Notice: Only variables should be passed by reference", so it should be formulated like this: </p>
  
  <pre><code>$numbers = range(11, 20); 
  shuffle($numbers);
  </code></pre>
  
  <p>As far as I've been working with PHP there are built-in functions that I would be able to connect (with each other). </p>
  
  <p>a) Are there any general rules related to this and is there a way I could find and explanation on the Net?</p>
  
  <p>b) How would you estimate the percentage of the functions that are connectible and the ones that are not?</p>
  
  <p>c) Could there be any other aspects like nesting deeper and this would not work (like chaining 10 separate functions would not work but they would work in pairs)? </p>
  
  <p>Thanks. </p>