Description:
------------
---
From manual page: http://www.php.net/language.operators.comparison
---

The example given for the null coalesce operator is not correct. This is the current example:

<?php
// Example usage for: Null Coalesce Operator
$action = $_POST['action'] ?? 'default';

// The above is identical to this if/else statement
if (isset($_POST['action'])) {
    $action = $_POST['action'];
} else {
    $action = 'default';
}

?>

It says that it is equivalent to using `isset()` in an if/else statement, but this is not true. If `$_POST['action']` would be set with the value `NULL` then the first expression would assign the value `default`, but the second would assign the value `NULL`.

In fact it is equivalent to using `!empty()`, so the example should be corrected to the following:

<?php
// Example usage for: Null Coalesce Operator
$action = $_POST['action'] ?? 'default';

// The above is identical to this if/else statement
if (!empty($_POST['action'])) {
    $action = $_POST['action'];
} else {
    $action = 'default';
}

?>

or possibly to the following, if we want to keep using `isset()` which is also mentioned elsewhere in the documentation:

<?php
// Example usage for: Null Coalesce Operator
$action = $_POST['action'] ?? 'default';

// The above is identical to this if/else statement
if (isset($_POST['action']) && !is_null($_POST['action'])) {
    $action = $_POST['action'];
} else {
    $action = 'default';
}

?>