This question already has answers here:
Weird PHP error: 'Can't use function return value in write context'
(12 answers)
Closed 6 years ago.
I get the error in the subject. Also I spent ages on google and found dozens of resources having the same error, but still I can't figure out what the issue is.
This is my code:
<?php
if(empty(trim($_POST["user"])) || empty(trim($_POST["text"]))) {
echo "no luck";
}
?>
PHP Fatal error: Can't use function return value in write context in
/var/www/test.php on on line 2
If you refer to a manual, you will see
Determine whether a variable is considered to be empty.
The result of trim passed to empty is not a variable.
So your options are:
$user = trim($_POST['user']);
if (!empty($user)) { }
Or php5.5, in which
empty() now supports expressions
Related
This question already has answers here:
Check if a variable is undefined in PHP
(8 answers)
Closed 4 years ago.
What's the best way of checking if an object property in php is undefined?
You can use is_null
Or
!isset($object)
Example :
I want to check if the input is undefined. So, I can show errors.
if (!isset($_POST['myInput'])) { echo "error"; } else { // do the code }
This question already has answers here:
PHP parse/syntax errors; and how to solve them
(20 answers)
Closed 4 years ago.
I don't know why the code below giving an error on my laptop while not at my friend's.
<?php
function myfunction() : int {
return 10;
}
echo myfunction();
?>
Error
Parse error: syntax error, unexpected ':', expecting '{' in (my location) on line 2.
If I remove the ": int" on line 2 everything is fine, but can someone explain why this code can't run on mine?
Please read the documentation. It is a PHP7+ only feature.
What might be a good idea as a work around, until you migrate to PHP7, is to do the following:
function myfunction() {
return (int)10;
}
var_dump(myfunction());
That will convert the return to an integer.
It's worth noting, this won't throw any warnings if the return value cannot be resolved.
I.E. If you passed parameters and those parameters were letters in a string, for instance, you'd get Warning: A non-numeric value encountered. However, for now, I think the above solution will suffice.
I strongly recommend upgrading to the latest version of PHP, though.
This question already has answers here:
Can't use method return value in write context
(8 answers)
Closed 8 years ago.
I have a if statement check to see if a string is empty
if(empty(strlen(trim($_POST['name'])))){
$error_empty = true;
}
gives me this error:
Fatal error: Can't use function return value in write context in C:\xampp\htdocs\requestaccess\index.php on line 51
empty is not a function -- it's a "language construct" that prior to PHP 5.5 can only be used to evaluate variables, not the results of arbitrary expressions.
If you wanted to use empty in exactly this manner (which is meaningless) you would have to store the result in an intermediate variable:
$var = strlen(trim($_POST['name']));
if(empty($var)) ...
But you don't need to do anything like this: strlen will always return an integer, so empty will effectively be reduced to checking for zero. You don't need empty for that; zero converts to boolean false automatically, so a saner option is
if(!strlen(trim($_POST['name']))) ...
or the equivalent
if(trim($_POST['name']) === '') ...
This question already has answers here:
Weird PHP error: 'Can't use function return value in write context'
(12 answers)
Closed 9 years ago.
This code:
if(!empty(trim($_POST['post']))){ }
return this error:
Fatal error: Can't use function return value in write context in ...
How can I resolve and avoid to do 2 checks ( trim and then empty ) ?
I want to check if POST is not only a blank space.
you cant use functions inside isset , empty statements. just assign the result of trim to a variable.
$r = trim($_POST['blop']);
if(!empty($r))....
edit: Prior to PHP 5.5
if (trim($_POST['post'])) {
Is functionally equivalent to what you appear to be trying to do. There's no need to call !empty
if (trim($_POST['post']) !== "") {
// this is the same
}
In the documentation it actually explains this problem specifically, then gives you an alternate solution. You can use
trim($name) == false.
In PHP, functions isset() and empty() are ment to test variables.
That means this
if(empty("someText")) { ... }
or this
if(isset(somefunction(args))) { ... }
doesn't make any sence, since result of a function is always defined, e.t.c.
These functions serve to tell wether a variable is defined or not, so argument must me a variable, or array with index, then it checks the index (works on objects too), like
if(!empty($_POST["mydata"])) {
//do something
} else {
echo "Wrong input";
}
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Any reason why Mage::registry(‘current_category’) would return NULL?
Reference - What does this error mean in PHP?
Fatal error: Call to a member function getParentCategory() on a non-object in...
the code:
$_category_detail=Mage::registry('current_category');
$id=$_category_detail->getParentCategory()->getId();
now, when the page can't use getParentCategory() i using the following but can't work.
if( isset(getParentCategory()){
$id=$_category_detail->getParentCategory()->getId();
}
why? thank you
It appears that $_category_detail is not an object. Therefore Mage::registry('current_category') is not returning an object.
It's most likely returning some sort of NULL or false value upon fail. And PHP is making you notice that (NULL)->getParentCategory() is meaningless.
In your particular case it returns NULL because current_category is not set in your registry.
You need to use method_exists() rather than trying to call a non-existent function:
if (method_exists($_category_detail, "getParentCategory"))
isset() only checks for member variables. Use method_exists().
PHP Manual: http://php.net/manual/de/function.method-exists.php
if (method_exists($_category_detail, 'getParentCategory')) {
$id = $_category_detail->getParentCategory()->getId()
}