Doc #75801 [Com]: Mistake in documentation example for null coalesce operator
| From: | pieter at frenssen dot be | Date: | Thu, 11 Jan 2018 13:28:00 +0000 |
| Subject: | Doc #75801 [Com]: Mistake in documentation example for null coalesce operator | ||
| References: | 1 | Groups: | php.doc.bugs |
| Request: | Send a blank email to doc-bugs+get-15329@lists.php.net to get a copy of this message | ||
Edit report at https://bugs.php.net/bug.php?id=75801&edit=1
ID: 75801
Comment by: pieter at frenssen dot be
Reported by: pieter at frenssen dot be
Summary: Mistake in documentation example for null coalesce
operator
Status: Open
Type: Documentation Problem
Package: Documentation problem
PHP Version: Irrelevant
Block user comment: N
Private report: N
New Comment:
Actually the first suggestion is not correct,
!empty() also returns TRUE if the value
would be set to 0 or FALSE.
So the second suggestion is the only correct one: isset($_POST['action']) &&
!is_null($_POST['action']).
Previous Comments:
------------------------------------------------------------------------
[2018-01-11 13:23:28] pieter at frenssen dot be
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';
}
?>
------------------------------------------------------------------------
--
Edit this bug report at https://bugs.php.net/bug.php?id=75801&edit=1