What is the point of assigning by reference?

This question already has an answer here:

How does the “&” operator work in a PHP function? 4 answers

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here's some examples:

Making aliases for very long variables

$config = array(
   'developers' =>  => array(
         'emails' => array()
      ),
);
$dev_emails = &$config['developers']['emails'];
$dev_emails[] = 'email1@tld.com';
$dev_emails[] = 'email2@tld.com';
$dev_emails[] = 'email3@tld.com';

Naming a single value with a different name

$result_count = mysql_num_rows();
$table_rows = &$number_of_results;

Assigning array items early

$post = $_POST;
$time = time();
$article = array(
    'article_contents' => &$post['contents'],
    'article_title' => &$post['title'],
    'article_tags' => &$post['tags'],
    'insert_time' => &$time
);

if (array_filter($article) < 3) {
   throw new Exception("Required fields are blank");
}

$post['contents'] = striptags($post['contents']);

# imaginary model
# article::insert($article);

^ This one seems to be impractical even to me, but I know this was useful to me for a number of times

Saving memory? ( just a theory )

There's still a lot more application that will only appear when you're coding, you'll notice where it's useful when you're already coding

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At one time, it was possible that this saved memory by avoiding copying long strings. But modern versions of PHP use copy-on-write, so this isn't as much of an issue.

That is, copy on write means if you assign $a = $b , it doesn't actually use more memory. $a internally points to the same content in memory that $b points to. But they're not supposed to be linked as though by reference. So if you modify $b , then at that moment PHP makes $a a physical copy of the original value of $b . If you modify $a , then it gets its own memory space for its new value.

References are still useful for side effects.

For example, when using foreach:

$a = array(1, 2, 3);

foreach ($a as $value) {
  $value *= 2; // does not change contents of $a
}

foreach ($a as &$value) {
  $value *= 2; // changes contents of $a
}

Or when passing function arguments, and you want the function to modify the value of the argument.

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