foreach loop and reference of &$value

Question

Why is an empty foreach loop can change the result.

I have the following code:

$variable = [1,2,3,4];
foreach ($variable  as $key => &$value)          


        

Answer 1

After loop you should unset this reference using:

unset($value);

So your whole code should work like this:

  $variable  = [1,2,3,4];
  foreach ($variable  as $key => &$value) {
    $value++;
  }
  unset($value);
  var_dump($variable); 

There is no point to put unset($value); inside the loop

Explanation - after loop $value is still set to the last element of array so you can use after your loop $value = 10; (before unset) and you will see that last element of array has been changed to 10. It seems that var_dump want to help us a bit in this case and shows there is reference for last element and of course when we use unset we have desired output of var_dump.

You could also look at the following script:

We don't use loop here and if reference is set to element of array, var_dump shows us this putting & before type of this element.

However if the above code we changed reference and set it this way $x = &$array; var_dump wouldn't show us any reference.

Also in the following code:

var_dump() won't give us any hint.