When is a PHP array not an array?

Jul 21, 2007 php

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Arrays, return variables, expressions, OH MY! I recently learned a lesson about array functions in PHP not returning what I thought they would. I had a function that returned the value of array_shift()… and then used it in another function. Unfortunately, this generated a strict error and was causing some issues… As usual, I put together a proof of concept. Let’s check out the code example, the error, and then why:

class TEST
{
  private $__data = '';
 
  public function __construct()
  {
    $this->__data = 'one,two,three';
  }
 
  public function getArray()
  {
    $a = array();
 
    $a[] = explode(',', $this->__data);
    $a[] = explode(',', $this->__data);
    $a[] = explode(',', $this->__data);
 
    return $a;
  }
}
 
function testFunction()
{
  $test = new TEST();
 
  return array_shift($test->getArray());
}
 
var_dump(testFunction());

When I execute this, I get a strict error:

**Strict Standards:** Only variables should be passed by reference in C:\DEVELOPMENT\temp\arraytest.php on line 27
array(3) { [0]=> string(3) "one" [1]=> string(3) "two" [2]=> string(5) "three" }

After talking with one of the consultants that (“the triangle”) uses, he sent me a note about all the things he found in regards to my test code.

First off, this bug page is from another developer that was running into the same issues as I was. After some back and forth, it looks like it’s just a mis-understanding … those functions are returning array pointers and not values and expressions (see expressions in PHP manual here).

Turns out that the way to fix this issue is going to be using pass by reference. One quick modification and we’re good:

public function &getArray()